isdn4k-utils/FAQ2/eng-i4l-faq.sgml

<!doctype linuxdoc system>

<article>

<title>FAQ for isdn4linux
<author>Matthias Hessler, <tt><htmlurl url="mailto:hessler@isdn4linux.de" name="hessler@isdn4linux.de"></tt>
<date>v2.0.5, 1. July 1999
<abstract>
This FAQ answers questions that were frequently asked in the newsgroup
de.alt.comm.isdn4linux. It contains questions any user should
know about ISDN under Linux using isdn4linux, as well as hints on how to
best make use of all the features isdn4linux provides.  

Version 2 of the FAQ is derived from an earlier version which had become
outdated at the time of this writing. To obtain information on old versions
of isdn4linux (1997 and earlier) please have a look at the FAQ version 1.3.4.

About the format of this FAQ:
The main basis of this FAQ is the i4l mailing list (see question
<ref id="docu_mailinglist">). I´ve treated the knowledge gained from reading as
public domain, without quoting the author of the original mail. The FAQ is now
written in SGML, as this format is flexible to convert into any other form of
documentation (though some restrictions apply). The FAQ is now maintained in
English since German-speaking people can easily follow the mailing
list/newsgroup (or search in the archives). Whoever wants to translate back to
German is welcome to do so!

The countless links in this documents are not always complete and I´m sure many
are no longer correct. I do not have the time to check them all. If you
discover a bad link, please let me know (I´ll try to install some automatic
checking when I have the time).

Additions, improvements and other suggestions are always welcome (also
correction of typographical errors!), preferably send "diffs" from the ASCII
version. Thank you very much in advance!

Send feedback about this FAQ to:
<tt><htmlurl url="mailto:i4lfaq@isdn4linux.de"
	     name="i4lfaq@isdn4linux.de"></tt>
or:
<tt><htmlurl url="mailto:hessler@isdn4linux.de"
	     name="hessler@isdn4linux.de"></tt>

The newest version of this FAQ can be found at:
<tt><url url="http://www.mhessler.de/i4lfaq.html"></tt>
or:
<tt><url url="http://www.isdn4linux.de/faq/"></tt>

This FAQ is protected by the GNU General Public License (GPL) Version 2;
(C) 1999 Matthias Hessler (for version 2.0)
Distribution under the terms of the GPL is welcome. However,
we offer NO GUARANTEES for the information herein. Please read the GNU
General Public License for further details. A printed version is available
from Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
An electronic version is available from the author.
</abstract>

<!-- Table of Content
-->

<toc>


<!-- General Section: About isdn4linux, features
-->

<sect> general: General information about isdn4linux
<label id="general">

<sect1> general_i4l: What is isdn4linux?
<p>
isdn4linux is a set of kernel modules which are part of the Linux
kernel. It consists of the main module <tt/isdn/ and the
actual hardware driver that control some specific card.
In addition, the package <tt/isdn4k-utils/ contains utilities to
make use of ISDN specific features.

<sect1> general_hardware: What hardware is supported by isdn4linux?
<p>
Generally, isdn4linux can control ISDN cards that are connected to the pc's
ISA or PCI bus. Also a few PCMCIA cards are supported. However, isdn4linux can
<bf/not/ make use of any devices connected via a serial or parallel
interface (which are called 'terminal adaptors'). For more details on which
cards are supported see section <ref id="hardware">.

<sect1> general_features: What features are supported by isdn4linux?
<p>
Basically, isdn4linux can receive and transmit data via ISDN in many ways
(X.75, HDLC, raw ip, synchronous ppp, asynchronous ppp). Some of its utilities
offer additional features. Two examples are <tt/isdnlog/, which allows to log
and react upon ISDN events (including calculating any charges); and <tt/vbox/
which provides voice answering machine capabilities. For more details see the
section <ref id="feature">.

<sect1> general_countries: Which countries are supported by isdn4linux?
<p>
At least all countries which use Euro-ISDN are supported, however some
pecularities apply. To find more about your country, check section
<ref id="countries">.

<sect1> general_docu: Where do I find more documentation, howto's, helpful tips
&amp; tricks?
<p>
Besides this FAQ have a look at the various man pages and Readme's that come
with the isdn4linux package. Then there is the isdn4linux website:
<url url="http://www.isdn4linux.de">. And there is also a news group and a
mailing list on isdn4linux which will give you the most up to date
information. To find out more about these great information sources, see
section <ref id="docu">.

<sect1> general_getlatest: Where do I get the latest version of isdn4linux?
<p>
The latest version of the kernel drivers should be found in the Linux
kernel. However, sometimes the Linux kernel does not have the latest version or
does not yet support your ISDN card. Additionally, you may need to use the
isdn4k-util package. In those cases you could try to get the very latest
version that is currently in development. See the section
<ref id="distrib">.

<sect1> general_contacts: How can I get in contact with the developers?
<p>
You can contact the isdn4linux developers through the www.isdn4linux.de
website. Have a look at <url url="http://www.isdn4linux.de/contacts">.


<!-- Development & Distribution -->

<sect> distrib: Distribution
<label id="distrib">

<!-- Who are the developers? -->

<sect1> distrib_getlatest: How can I get the latest isdn4linux?
<p>
You can find the kernel source it in any kernel, however it may be outdated. To
get a newer version, as well as the utility package you have several options.
<enum>
<item><bf>Via CVS:</bf>
See question about access to CVS, which the developers use to merge their
latest code: <ref id="distrib_cvs">.
<item><bf>Via FTP:</bf>
There is a list of mirrors of the cvs tree; check:
<tt><url url="http://www.isdn4linux.de/download.php3"></tt>.
</enum>

<sect1> distrib_cvs: How can I access the source from the current
development/what is the CVS tree all about?
<label id="distrib_cvs">
<p>
CVS - Concurrent Version System

This is a multiuser/server extension to RCS (Revision Control System).
The I4L drivers are developed under CVS, and there exists on server
(cvs.isdn4linux.de) a CVS tree to which all developers have access.
In addition, Fritz has put together an anonymous read-only access. If you
must have the very newest versions, you can get them there, however they
may contain more bugs than the released versions!!!

Here is how to get the latest version:
<enum>
<item>Create and go to the directory where you want to store i4l
<code>mkdir ~/cvs; cd ~/cvs</code>
<item>Set CVSROOT to <tt>:pserver:guest@cvs.isdn4linux.de:/i4ldev</tt>
<code>export CVSROOT=:pserver:guest@cvs.isdn4linux.de:/i4ldev</code>
<item>Login in (asks for a password, any password will work)
<code>cvs login</code>
<item>Get the isdn kernel driver stuff (same hierarchy as in the linux source)
<code>cvs checkout isdn</code>
<item>Get the utility package into the current directory
<code>cvs checkout isdn4k-utils</code>
If you want to get the latest version for kernel 2.0.x rather than for the
latest kernel, then you have to give the additional option `-r':
<code>cvs checkout -r isdn4kernel_2_0 isdn</code>
</enum>

WATCH OUT!!! THE NEWEST STUFF SOMETIMES IS REALLY INSTABLE OR EVEN
DOES NOT COMPILE WITHOUT PROGRAMMING KNOWLEDGE -
No newbies questions on this PLEASE! Use the source, Luke!

People who want to help <em>continuously</em> developing isdn4linux by writing
new driver etc. can get a real account for full access. In this case write
an email to Fritz Elfert <tt><htmlurl url="mailto:fritz@isdn4linux.de"
name="fritz@isdn4linux.de"></tt>


<!-- Features
-->

<sect> Features
<label id="feature">

<sect1> feature_not: Which ISDN features can not be offered by isdn4linux?
<p>
Some ISDN features are device-specific and cannot be activated by
isdn4linux for other devices, unless isdn4linux were to falsify 
the TEI (which would probably confuse the other device).
Such device-specific ISDN features are, among others: rejection of a
waiting call, caller id on/off, hold, conference calls, differing COLP/CLRP.

<sect1> feature_data: Which ISDN data transmission modes are supported?
<p>
These low-level formats are possible:
<itemize>
<item> 56k asynchronous : no
<item> 64k synchronous  : yes
<item>128k synchronous  : yes (channel bundling - see the question <ref id="feature_2channel">)
</itemize>
These level2 formats are possible:
<itemize>
<item>HDLC
<item>X.75
<item>transparent
</itemize>
These encapsulations are possible:
<itemize>
<item>rawip
<item>ethernet
<item>Sync PPP
<item>X.25 (requires 2.1)
<item>cisco and cisco-h
<item>plus a few specialities.
</itemize>

<sect1> feature_voice: Can I use isdn4linux as an answering machine?
<p>
Yes, voice support is possible with the current version of isdn4linux.
You can either use &dquot;vgetty&dquot; from Gert Doerings &dquot;mgetty+sendfax&dquot;, 
or &dquot;vboxgetty&dquot; from Michael Herold, which is made especially for
isdn4linux.
The latter can be found at:
<tt><url url="ftp://ftp.franken.de/pub/isdn4linux/contributions/"></tt>

<sect1> feature_fax: Can I fax with isdn4linux?
<p>
<itemize>
<item><bf>For all passive cards: NO</bf>. However, there is a project working
on this rather complicated problem. For more info on its status have a look at:
<tt><url url="http://home.telia.no/Morten.Rolland/linux/i4lfax/index.html"></tt>
<item><bf>For the active card AVM B1: Yes</bf> (its firmware has implemented
fax as one of its features).
</itemize>
If you do want to fax now, your best choice is to install an analog fax modem
along with your ISDN card.

<sect1> feature_divert: Is it possible to initiate call forwarding with i4l?
<p>
Call diversion features are implemented in the latest cvs tree version for
kernel 2.0.x (but not 2.1/2.2/2.3). Use the new program <tt/divertctrl/. So far
no howto and little documentation does exist for it, therefore currently this
is something for the more experienced user. In the Netherlands, the keypad
protocol can be used alternatively.

<sect1> feature_ipx: Can I route ipx/spx over ISDN with Linux?
<p>
Yes, just set up an ISDN interface with encapsulation
<tt/ethernet/. <em/mars_nwe/ can do the rest (e.g. routing). Also, you can
route ipx with ipppd, see question <ref id="syncppp_ipx">.

<sect1> feature_2channel: Does isdn4linux support channel bundling?
<label id="feature_2channel">
<p>
The current version of isdn4linux support 2 methods of channel 
bundling:
<itemize>
<item><bf>MPPP</bf> (based on sync PPP)
<item><bf>Raw bundling</bf> (configured by so-called slave channels)
</itemize>
Both variants have their own advantages and disadvantages  See the question &dquot;
How do I use channel bundling?&dquot; in the &dquot;Channel bundling&dquot; section below.
Warning: Channel bundling saves time, but not any telephone charges.
Only if you really need the extra bandwidth is it useful.

<sect1> feature_diald: Can I combine isdn4linux with diald?
<p>
Yes, see the &dquot;Diald&dquot; part of the &dquot;Configuration&dquot;
section.

<sect1> feature_dod: Does the driver support &dquot;dial on demand&dquot;?
<p>
Yes. If a network interface (e.g. &dquot;isdn0&dquot;) is set up, the driver
will dial the number. If in addition a hangup timeout (Idle Timeout) has been
given, isdnctrl huptime interface time, then the driver will automatically hang
up when no data was been transferred over the interface for &dquot;time&dquot;
seconds. However, with syncPPP there are problems (see the syncPPP section).
Also look at the dialmode description (see question <ref id="config_dialmode">).
You may also be very interested in the big part of this FAQ that handles
unwanted dialouts... (<ref id="dod">)

<sect1> feature_btx: Is the German videotex/Btx/Datex-J possible with isdn4linux?  
<p>
Yes, it works with the modem emulation with the ttyI* devices. There is
a special register to set for videotex (ATSx=y -  see the Readme's)
Warning! XCept (formerly Xbtx) has an ISDN configuration option. This
should NOT be used. XCept should be configured as if a normal modem
were being used.

<sect1> feature_clock: How can I set the clock of my computer with ISDN?
<p>
Isdnlog offers this feature with option &dquot;-t&dquot;. Unfortunately, the
seconds are not transmitted via ISDN, and the transmitted time is
not very accurate - depending on the ISDN equipment of your
telephone company there may be a deviation of several minutes (!).
It's better to get a PC clock that is set by radio signals and
check it with, for example, xntp. You can also use a time server in
the Internet with &dquot;netdate&dquot; or &dquot;rdate&dquot;. One time server
can be found in Cologne: time.rrz.uni-koeln.de, but there are many more.

<sect1> feature_dosemu: Can I use isdn4linux under dosemu?
<p>
Yes, you really can! Steffan Henke <tt><htmlurl url="mailto:henker@informatik.uni-bremen.de"
name="henker@informatik.uni-bremen.de"></tt>
wrote on 25 Oct 96:
<quote>
In dosemu.conf it is enough to enter a virtual com port,
(for example com2) that can be used with e.g. Telix or
Terminate: serial { com 2 device /dev/ttyI3 }
Access with Fossil is possible if fossil.com (included with
dosemu) is started.  Tested with the following configurations: 
- Kernel 2.0.21, Teles driver incl. Karsten's patches 
- Kernel 2.0.21, HiSax
</quote>   

<sect1> feature_rawip: What is Raw IP, when should I use it?
<p>
Raw IP does without the use of a protocol such as X.75 or HDLC
(for modem emulation, etc.) or PPP. TCP/IP packets are directly
exchanged.
Raw IP has both advantages and disadvantages.
Advantages:
<itemize>
<item> No handshaking (= faster connections)
<item> Authorization by Caller ID (= fast, safe, no password)
<item> Fixed IP address (= a broken connection can be continued by redialing)
<item> Higher data transfer rates
<item> Better stability (smaller driver = almost no bugs)
</itemize>
Disadvantages:
<itemize>
<item> No handshaking 
= Configuration must occur beforehand (IP addresses,...)
= sensible to use for only for one provider at a time 
<item> Authorization only by Caller ID
= Dialin only possible from one's own number
<item> Fixed IP address
= must be known ahead of time, more IP addresses required, no dynamic
assignment of addresses possible.
</itemize>
From this summary it should be clear under what conditions it makes sense
to use raw IP.

<sect1> feature_capi: Is there a CAPI interface available?
<p>
Currently, there is a CAPI 2.0 interface for the active card AVM B1, but not
for any other card. However, there are plans to make this a general interface,
also for other cards. There are no plans to implement a CAPI 1.0 interface.

<!-- Feature reversed card -->

<!-- Chargeint -->

<!-- Feature Raw-IP -->

<!-- Feature both caller ids -->

<!-- Feature leased line -->

<!-- Eurofile -->


<!-- Helpful docu, links, mailing list, config examples, howto's -->

<sect> docu: Documentation, Howto's, Tips &amp; Tricks, Mailing List/Newsgroup
<label id="docu">

<sect1> docu_first: What documents should I read first?
<p>
<itemize> 
<item>ISDN kernel subsystem:
/usr/src/linux/Documentation/isdn/README
<item>ISDN cards:
/usr/src/linux/Documentation/isdn/README.card
E.g.: /usr/src/linux/Documentation/isdn/README.HiSax
<item>Synchronous PPP:
/usr/src/linux/Documentation/isdn/README.syncppp
/usr/src/linux/Documentation/isdn/README.syncPPP.FAQ
<item>Voice capability:
/usr/src/linux/Documentation/isdn/README.audio
<item>ISDN Utilities:
/usr/src/isdn4k-utils-version/README(.*)
</itemize>
Many of the utilities also have man pages!

In a Suse distribution the following information might also be helpful:
<itemize>
<item>Synchronous PPP:       /usr/doc/faq/faq/PPP-FAQ
<item>Email configuration:  /usr/doc/howto/mini/Mail-Queue.gz
</itemize>

<sect1> docu_newsgroup: Where is the official website for isdn4linux? 
<p>
The offical website can be found at:
<url url="http://www.isdn4linux.de">.

<sect1> docu_newsgroup: Where is the newsgroup for isdn4linux? 
<p>
The newsgroup is <tt/de.alt.comm.isdn4linux/. Most isdn4linux developers are
present, and many other knowledgeable people. Don't be confused by the many
German messages on it. <bf>English postings are very welcome, and will be
answered in english!</bf>

<sect1> docu_mailinglist: Where is the mailing list for isdn4linux?
<label id="docu_mailinglist">
<p>
The mailing list contains the same messages as the newsgroup. A bidirectional
gateway ensures that both are in sync.
To subscribe to the mailing list, send an email message to 
<tt><htmlurl url="mailto:majordomo@listserv.isdn4linux.de"
name="majordomo@listserv.isdn4linux.de"></tt>.
The subject doesn't matter. The message body should read <tt/subscribe
isdn4linux &lt;email address&gt;/, where &lt;email address&gt; is the
address to which mail from the list should be sent. To unsubscribe send a
message with the body <tt/unsubscribe isdn4linux &lt;email address&gt;/ at the
same address. Please note: there are about 20-50 messages per day on this
mailing list.

<sect1> docu_mailarchive: Is there an archive of the isdn4linux mailing list?
<p>
To quickly search for keywords, you can make use of
<tt><url url="http://www.deja.com"></tt>. Make sure to also select older
archive to do a complete search.

Messages are also saved (unsorted) at listserv.isdn4linux.de, collected by
month. To access the archive, send Email to
<tt><htmlurl url="mailto:majordomo@listserv.isdn4linux.de"
name="majordomo@listserv.isdn4linux.de"></tt>.
The subject doesn't matter. These commands are possible: 
<itemize>
<item>index isdn4linux - list which archive files are available
<item>get isdn4linux filename - retrieves the file filename
</itemize>
The archives are named &dquot;archiv.yearmonth&dquot;, so
&dquot;archiv.9610&dquot; is the archive for October 1996.

Other archives are:
<itemize>
<item><tt><url
url="ftp://ftp.uni-oldenburg.de/pub/unix/linux/isdn/isdn4linux/Mailing-List"></tt>
<item><tt><url url="http://wws.mathematik.hu-berlin.de/ldr/ISDN/isdn4linux/"></tt>
</itemize>


<!-- Supported Hardware & hardware-specific stuff
-->

<sect> hardware: Supported hardware, its specialities, and hardware-related
problems
<label id="hardware">

<sect1> hardware_support: What hardware is supported?
<p>
Only internal cards that plug into an ISA or PCI slot are
supported. ISA Plug&amp;Play cards are also supported, but need some additional
manual configuration by means of the <tt/isapnptools/. For details on the
configuration see question <ref id="config_pnp">.

Right now there is a driver for all passive card with certain Siemens
chipsets (HiSax driver). Have a look at the <tt/README.HiSax/ that comes with
the driver for the most up to date information on supported cards.
Here the latest status (8th June 1999):
<itemize>
<item>Teles 8.0/16.0/16.3 and compatible ones (like: Dr. Neuhaus Niccy
1016, Creatix 16/S0)
<item>Teles 16.3c (can not be used as reversed card)
<item>Teles S0/PCMCIA
<item>Teles PCI
<item>Teles S0Box
<item>Creatix S0Box
<item>Creatix PnP S0
<item>Compaq ISDN S0 ISA card
<item>AVM A1 (Fritz, Teledat 150)
<item>AVM Fritz PCMCIA
<item>AVM Fritz PnP
<item>AVM Fritz PCI
<item>ELSA Microlink PCC-16, PCF, PCF-Pro, PCC-8
<item>ELSA Quickstep 1000
<item>ELSA Quickstep 1000PCI
<item>ELSA Quickstep 3000 (same settings as QS1000)
<item>ELSA Quickstep 3000PCI
<item>ELSA PCMCIA
<item>ITK ix1-micro Rev.2
<item>Eicon.Diehl Diva 2.0 ISA and PCI (S0 and U interface, no PRO version)
<item>Eicon.Diehl Diva Piccola
<item>ASUSCOM NETWORK INC. ISDNLink 128K PC adapter (order code I-IN100-ST-D)
<item>Dynalink IS64PH (OEM version of ASUSCOM NETWORK INC. ISDNLink 128K
adapter)
<item>PCBIT-DP (OEM version of ASUSCOM NETWORK INC. ISDNLink)
<item>HFC-2BS0 based cards (TeleInt SA1)
<item>Sedlbauer Speed Card (Speed Win, Teledat 100, PCI, Fax+)
<item>Sedlbauer Speed Star/Speed Star2 (PCMCIA)
<item>Sedlbauer ISDN-Controller PC/104
<item>USR Sportster internal TA (compatible Stollmann tina-pp V3)
<item>ith Kommunikationstechnik GmbH MIC 16 ISA card
<item>Traverse Technologie NETjet PCI S0 card
<item>Dr. Neuhaus Niccy PnP/PCI
</itemize>
Note:
<itemize>
<item>PCF, PCF-Pro: up to now, only the ISDN part is supported
<item>PCC-8: not tested yet
<item>Teles PCMCIA is EXPERIMENTAL
<item>Teles 16.3c is EXPERIMENTAL
<item>Teles PCI is EXPERIMENTAL
<item>Teles S0Box is EXPERIMENTAL
<item>Eicon.Diehl Diva U interface not tested
</itemize>

A few active cards that are also supported, see next question.

<sect1> hardware_activepassive: What is the difference between an active and a passive ISDN card?
<p>
An active ISDN card handles most of the ISDN connection protocols 
(dialing, accepting calls, etc.) itself. The card includes a kind 
of minicomputer with its own software (firmware). With a passive card, the
computer in which the card is installed has to perform these functions.

In principle, both types are supported by isdn4linux. However, since active
cards have non-standard interfaces, a driver can only be made when the producer
publishes the interface. Also, the card's firmware needs to be made freely
available. In contrast, many passive cards share the same chipset. Therefore
many passive cards can be supported once a driver supports this one chipset.

These active cards are currently supported by an individual driver:
<itemize>
<item>AVM B1
<item>ICN
</itemize>

<sect1> hardware_recommend: Which card is recommended by the developers?
<p>
The developers suggest to use ELSA cards. ELSA has made their specifications
available to the developers, and provided a lot of support, resulting in an
excellent driver. Also, their cards are certified for usage in Germany, see
question <ref id="country_certified">.

<sect1> hardware_external: Does isdn4linux support external terminal adapters?
<p>
No, but it doesn't need to. Terminal adapters are designed to behave
either like a modem or like a network card. Linux already supports both
modems and network cards without isdn4linux - so no special ISDN driver
is necessary (which usually greatly simplifies the configuration).

<sect1> hardware_irq: Why should I avoid IRQ 12 and 15 for my ISDN card?
<p>
On many PCI boards, interrupt 12 is often used by a PS/2 mouse (even though you
may not have any or the IRQ is not activated for it). It may be used even when
you have no PS/2 port. Interrupt 15 is also often used by the second IDE bus
(even when you are not using it or the IRQ is not activated for it).
Even though one thinks that some IRQs are available they are still somehow
reserved by the BIOS. Good IRQs to try are always IRQ 5 and IRQ 9. Without mice
or modems you could also try 4 and 3, which works even on very exotic boards.

<sect1> hardware_alpha: Can I run isdn4linux on a DEC Alpha with Linux?
<p>
Yes, most cards should run with isdn4linux on a DEC Alpha. Many cards have been
reported to work with the HiSax driver. Also the active ICN card has been
reported to work.

<sect1> hardware_maxcards: How many ISDN cards can I put into my computer?
<p>
It depends on the availability of slots, interrupts/IO addresses in your
computer as well as the possibilities of the ISDN card. Most passive cards
are limited by the supported IO addresses (e.g.: Teles 16.x: only 3 addresses
are legally possible), and the total usage of interrupts (every card needs one).

To use more cards, the ICN card may be your choice. It has no interrupts, a
more flexible port configuration and the driver places the shared memory area
of all ICN cards at the same address. The card memory is shown only as
needed. Therefore, one can use as many cards are there are slots.

<sect1> hardware_teles: What should I know about before buying an ISDN card from Teles?
<p>
Teles´ business practices are very customer- and developer-unfriendly when
compared to those of other companies. Naturally, the developers give
priority to cards for which support is available, and where the specifications
are freely available.

So far, Teles has had a very unfriendly attitude towards the i4l
developers. No support has ever been received from them, and they don´t publish
any information about how to access their card. The developers have invested a lot
of private effort into getting this card to work from the beginning without
receiving any support. The driver has been a complete private effort. Yet,
Teles has bragged on their web site that their cards run under Linux, without
giving proper credit.

Even companies that buy Teles cards and resell them under their own name have
not been able to improve the support. This has lead to the situation where a
re-branding company (!) itself had to go through the effort of obtaining
approval to legally use i4l in Germany on a Teles card.

From a customer point of view, check out the prices for their hotline before
you buy any hardware from them! The author of the FAQ refuses to use any
hotline that charges 216,- DM per hour. Reports about quality and waiting time
have not always been favorable.

Warning: Teles has often changed their cards without notice, while still
using the same name. When you buy a Teles card, you may find out that your
brand-new card can not be supported by i4l!

The developers will try to support new Teles cards when information about how
to access it becomes available, and when they have no other priorities. Of
course you can always send a patch.

<sect1> hardware_icn: What is special about the ICN card?
<p>
This was the first active card supported by isdn4linux. The manufacturer has
always supported i4l developers (<tt><url url="http://www.think.de/"></tt>).
The ICN does not need any interrupt (polling), therefore a PC can be equipped
with many of them without any interrupt conflicts. The newest firmware should
be available at <tt><url url="ftp://ftp.think.de/pub/isdn4linux/firmware/"></tt>.
Unfortunately, the ICN is not produced any more.


<!-- Trouble Hardware
-->

<sect1> hardware_crossedcable1: If i4l uses one B-channel then the other one
will be blocked (incoming as well as outgoing)...
<p>
This behavior is typical for a cable with confused a/b wiring. Some
NT from Quante had a wrong labeling. They caused exactly the
mentioned behavior if the PBX was connected to the plug of the NT
and the ISDN card to the pins of the NT. As soon as some device
activates the bus the other one can no longer get through.

<sect1> hardware_crossedcable2: How can I test whether a a/b cable pair has been crossed?
<p>
This question assumes that you are connected by an internal bus that you
installed, attached directly to the NT (without using an RJ45 cable).

The easiest way to test it is to buy a little cable tester (the author of this
FAQ got one from Conrad Electronics in Germany for 29,- DM - just follow the
simple instructions).

Otherwise you have a bit more work. Switch line a1 and b1. If it doesn't work,
put them back and switch a2 and b2. If it still doesn't work, try switching
them both. As long as {a|b}1 and {a|b}2 are kept, nothing can break. If you
want to be sure, before plugging it in measure between pins 4 and 5 and between
Pins 2 and 6 on the socket; there should be no current, but between 3 and 4 and
between 6 and 5 should be 40 V, 6 and 3 positive.

With the Western plug this works similar. 4 lines are used:
<verb>
| | | | 
| | | |
1 2 3 4
</verb>
Then you can try to switch (1 with 4) or (2 with 3) or both. Never switch the
outer with the inner lines - this would cross the RX and TX lines and nothing
will work.

Check the Cable FAQ for more details on which line should be connected how.

If both devices are attached via RJ45, then one of the cables
has been twisted. That usually happens if one of the RJ45 plugs
has been attached upside-down (a1/b1 are inside, a2/b2 are outside,
so the order of the sending/receiving pairs is maintained), then
you just need a new plug and of course pliers for the RJ45, old
plug off, and new plug (in the right direction) on.

<sect1> hardware_pbx: i4l is working on the internal bus of a PBX. Any problem?
<p>
Many PBX run non-standard ISDN protocolls on their internal bus. This may cause
i4l to print warnings when it encounters unexpected frames (some old versions
even crash). Also, they may run 1TR6 protocoll by default, instead of Euro ISDN
on their internal bus. You have to configure i4l (or the PBX) accordingly, best
is you try both on the same or similar protocolls.

Also the MSN may be different than you expect. Check several versions, one
digit, or two digits, or whole MSN. Best is you call some device (e.g. ISDN
telephone) on the internal bus and check what i4l writes into the log file.

<sect1> hardware_telestrouble: The PNP tools done work with my Teles 16.3 PNP card!
<p>
It's probably not a Plug 'n Play card at all - even though Teles
now prints PNP on all their card and packaging. The difference is easy
to recognize: a real Teles PNP card no longer has the (tiny) Dip switches
on the card to set the IO addresses.

<sect1> hardware_elsacabletrouble: On my ELSA card, the LED for the loss of the
TEI often blinks. My connections are also often disrupted...
<p>
These blinking LEDS are often caused by a bad cable or a too long or
unterminated SO bus.

<sect1> hardware_elsairq: My ELSA Quickstep 1000 ISA card produces very many
interrupts with the HiSax driver. Is this normal or a problem with the HiSax driver?
<p>
This is normal. The ELSA Quickstep 1000 ISA card has a hardware timer on the
card which can not be disabled by software. You have to modify the card
hardware to get rid of it. Check with Karsten Keil for this:
<tt><htmlurl url="mailto:keil@isdn4linux.de" name="keil@isdn4linux.de"></tt>



<!-- Configuration/Troubleshooting
-->

<sect> config: General information about Configuration

<sect1> config_msn: How should I set up isdn4linux with my MSNs?
<p>
See section <ref id="msn">.

<sect1> config_hardware: How should I configure my hardware? Is there something special I should
know about my ISDN card?
<p>
Have a look in section <ref id="hardware">.

<sect1> config_dialmode: When an IP packet should go over the link (which usually triggers a
dialout), all I see in the log is: &dquot;dial rejected: interface not in
dialmode `auto'&dquot;?
<label id="config_dialmode">
<p>
The new ISDN drivers in 2.0.36 defaults to manual dialmode, not
autodial. This is done to prevent unexpected (and unnoticed) dialouts.

To enable autodial for a given interface e.g. ippp0, use
<code>isdnctrl dialmode ippp0 auto</code>

The meaning of the values for dialmode is:
<descrip>
<tag/off/
means that you (or the system) cannot make any connection
(neither incoming nor outgoing connections are possible). Use
this if you want to be sure that no connections will be made.

<tag/auto/
means that the interface is in auto-dial mode, and will
attempt to make a connection whenever a network data packet needs
the interface's link. Note that this can cause unexpected dialouts,
and lead to a high phone bill! Some daemons or other pc's that use
this interface can cause this.
Incoming connections are also possible.

<tag/manual/
(DEFAULT) is a dial mode created to prevent the unexpected dialouts.
In this mode, the interface will never make any connections on its
own. You must explicitly initiate a connection with:
<code>isdnctrl dial ippp0</code>
Please note that the <tt/huptimeout/ may still end the connection
automatically! To ensure that you have to hang up manually, you have to switch
this off:
<code>isdnctrl huptimeout ippp0 0</code>
To end the connection, use:
<code>isdnctrl hangup ippp0</code>
</descrip>
To allow a normal user to initiate a dialout, have a look at question
<ref id="config_permission">.

<sect1> config_permission: How can I allow a normal user to initiate dialouts?
<label id="config_permission">
<p>
ISDN usage depends on the permissions to the devices <tt>/dev/ttyI*</tt> and
<tt>/dev/cui*</tt>. You have several choices to selectively allow users to do
ISDN transactions.
<enum>
<item>You can establish the group `isdn' in <tt>/etc/group</tt>, and do:
<code>
chgrp isdn /dev/ttyI* /dev/cui*
chmod o-rw /dev/ttyI* /dev/cui*
</code>
Then all users not in the group 'isdn' have no reading or writing 
privileges for the ISDN ttys. Those allowed to use ISDN have to be
explicitly added to the group 'isdn'.
<item>You can allow only root to log out, but set up exceptions for other users
with the su1 functionality (see man su1). As root edit
<tt>/etc/su1.priv</tt>. Add these lines if they (or similar ones) are not yet
there, to allow users XXXX and YYYY to initiate dialups/hangups:
<code>
# log all dialouts in syslog
syslog all
define PPPUSER XXXX YYYY
alias dial /sbin/isdnctrl dial ippp0
alias hangup /sbin/isdnctrl hangup ippp0
ask never
allow PPPUSER prefix dial
allow PPPUSER prefix hangup
</code>
Then create two links for dial and hangup:
<code>
ln -s /usr/bin/su1 /usr/local/bin/dial
ln -s /usr/bin/su1 /usr/local/bin/hangup
</code>
Now the users XXXX and YYYY can dial out by typing <tt/dial/, and hangup with
<tt/hangup/.
<item>If you only have one user that you use for ISDN interactions, you can
make him owner of the ISDN interface.
</enum>

<sect1> config_pnp: How do I configure a PNP (Plug and Play) card?
<label id="config_pnp">
<p>
For PCI cards Plug and Play works automatically, they don´t need any manual
configuration if the correct card type is provided. ISA PNP cards will
require some manual configuration:
<enum>
<item>With &dquot;make menuconfig&dquot; (or &dquot;make config&dquot;) set the
following kernel options:
<itemize>
<item>ISDN = &dquot;M&dquot; (as module - otherwise PNP doesn't work!)
<item>HiSax = &dquot;M&dquot; (as module - otherwise PNP doesn't work!)
<item>16.3/PNP support
<item>EURO support
</itemize>
<item>Compile and install kernel and modules, depmod. (Reboot!)
<item>Read the configuration of the PNP card with:
<code>pnpdump &gt; /etc/isapnp.conf</code>
<item>The configuration file <tt>/etc/isapnp.conf</tt> has to be set by
hand. Set the following values:
<itemize>
<item>INT0 - the interrupt used by the card (Default for Teles 16.3 PNP: 10)
<item>IO0, IO1 - the IO ports used by the card (Default for Teles 16.3 PNP:
0x580 and 0x180) (Attention: these values must be 64-bit aligned (ending with
0, 4, 8, or c)! Early versions of the PNP cards may suggest incorrect values!)
<item><bf>Remove comment in front of ACT Y!</bf>
</itemize>
<item>Activate the configuration with:
<code>isapnp /etc/isapnp.conf</code> (must be started at every boot)
<item>Now the HiSax module can be started for Euro-ISDN with:
<code>modprobe hisax io=4,2,INT,IO0,IO1</code>
(Replace INT, IO0, and IO1 with the your values in isapnp.conf.)
</enum>

<sect1> config_kerneld: Why shouldn´t I use <em>kerneld</em> to load the ISDN
modules in the kernel as needed?
<label id="config_kerneld">
<p>
<em>kerneld</em> does not work well with the ISDN modules, since the ISDN
modules can not store their status, and could miss important messages on the
D channel. Newer versions of i4l ensure that they won´t be unloaded by
kerneld, but you should not try to use kerneld with any version of i4l.


<sect1> config_runlevel: How can I boot Linux sometimes with
ISDN, and sometimes without?
<label id="config_runlevel">
<p>
Yes, you can define two different run level for this (under SysVInit) in
<tt>/etc/inittab</tt>. One run level includes the ISDN processes, where the
other one does not.

<!-- links outdated? - may need to be reworked! -->

<sect1> config_links: What helpful links are there about isdn4linux?
<p>
Please note: these link list may be outdated, they have not been checked for a
long while.
<itemize>
<item>Scripts and installation tips from several people:
<tt><url url="http://www.rosat.mpe-garching.mpg.de/&tilde;web/ISDN.html"></tt>
<item>I4l, syncPPP, email, Usenet, Voicebox, this FAQ and more:
<tt><url url="http://www.lrz-muenchen.de/&tilde;ui161ab/www/isdn/"></tt>
<item>Michael Hipp's page (general informations):
<tt><url url="http://www.sfs.nphil.uni-tuebingen.de/&tilde;hipp/isdn/"></tt>
<item>Chargeint instructions:
<tt><url url="http://www.provi.de/&tilde;gvz/chargeint.html"></tt>
<item>Stefan Nehlsen's instructions for syncPPP:
<tt><url url="http://www.techfak.uni-kiel.de/&tilde;stn/i4l/"></tt>
<item>xled (formerly xvboxled) is at:
<tt><url url="http://fb4-1112.uni-muenster.de/pub/ffwd/"></tt>
<item>Example configurations for isdn4linux are said to be at:
<tt><url url="http://www.datenhighway.com/isdn4linux.html"></tt>
<item>This FAQ along with isdn4linux is at:
<tt><url url="ftp://ftp.franken.de/pub/isdn4linux/"></tt>
<item>This FAQ is also so:
<tt><url url="ftp://ftp.pop.de/pub2/linux/isdn4linux/FAQ"></tt>
<item>Configuration examples and scripts: 
<tt><url url="http://www.rosat.mpe-garching.mpg.de/&tilde;web/ISDN.html"></tt>
<item>Many HowTo's on basic installation, syncPPP, Email setup, 
Usenet News, answering machine, and more:
<tt><url url="http://www.lrz-muenchen.de/&tilde;ui161ab/www/isdn/"></tt>
<item>Further FAQs with example scripts:
<tt><url url="http://www.fzi.de/sim/people/trautw/i4l/index.html"></tt>
<item>Eurofile client + server software (alpha):
<tt><url url="ftp://ftp.hamburg.pop.de/pap/LOCAL/linux/i4l-eft/"></tt>
</itemize>

<sect1> trouble_tcpdump: Why does my tcpdump not work for ip packets going over
ISDN? How can I get a tcpdump patched for ISDN?
<label id="trouble_tcpdump">
<p>
The reason is that tcpdump does not always understand the special
encapsulations that are possible with isdn4linux, especially syncppp. To change
this, you need to patch tcpdump.

Michael Stiller <tt><htmlurl url="mailto:michael@toyland.ping.de"
name="michael@toyland.ping.de"></tt> wrote on 23 Oct 1996:

Tip for ftp:

<tt><url url="ftp://ftp.gwdg.de/pub/misc/isdn/linux/isdn4linux-gwdg"></tt>

There is the patch: &dquot;tcpdump-3.0.4-1-isdn.dif.gz&dquot;

and the rest is at:

/pub/linux/mirrors/funet/PEOPLE/Linus/net-source/tools/tcpdump-3.0.4-1.tar.gz

You might need to hack some, depending on the name of your ISDN interface
(mine is bri0). By default, it recognizes only isdn* and isdnY* as 
interface names.

Henning Schmiedehausen <tt><htmlurl url="mailto:henning@pong.iconsult.com"
name="henning@pong.iconsult.com"></tt> further wrote on
30 Oct 1996:
<quote>
After finding the patch from Eberhard Moenkeberg at ftp.gwdg.de cannot
dump cisco HDLC, I made my own patch for tcpdump-3.0.4 that asks the
interface which encapsulation it used and sets itself accordingly. The
patch is against a tcpdump-3.0.4-1.tar.gz distribution, for example at
</quote>
<tt><url url="ftp://ftp.funet.fi/pub/Linux/PEOPLE/Linus/tools"></tt> 
<quote>
This patch recognizes rawIP, ISDN-IP and CISCO-HDLC and can
dump these packets.
</quote>
(The patch was attached to the message  - it should be easy to find in the 
mailing list archive - Ed.)

Sascha Ottolski <tt><htmlurl url="mailto:sascha@alzhimer.isdn.cs.tu-berlin.de"
name="sascha@alzhimer.isdn.cs.tu-berlin.de"></tt> gave the following
tip on 5 Nov 1996:
<quote>
This is a isdn4k-utils-2.0/tcpdump-3.0.3-isdn.diff ! It work,
if one makes some changes:
In the file tcpdump-3.0.3-isdn/libpcap-0.0/pcap-linux.c after patching
you find the following:
else if (strncmp(&dquot;ppp&dquot;, device, 3) == 0)
Either you name your ppp devices pppX instead of ipppX, or
change this line, e.g.
else if (strncmp(&dquot;ippp&dquot;, device, 4) == 0)
^^^^          ^^
Then tcpdump will also recognize syncPPP. At least it does for me.
</quote>


<!-- Config MSN
-->

<sect> msn: Configuration/MSNs
<label id="msn">

<sect1> msn_my1: What is my MSN? What if I don´t have any?
<p>
Your telephone company will tell you your MSN. It is your own telephone
number. Please note that you <bf/have/ to provide i4l with at least one MSN. If
you don´t have any you can use `0', which is assumed if no MSN is transmitted
from your telephone company. Check section <ref id="countries">, together with
the following questions, on how to configure your MSN(s).

<sect1> msn_my2: How can I find out how my telephone number is transmitted
to the calling party?
<p>
The transmitted MSN can simply be determined by calling yourself
(for example by telephone). In the log files you will find the
entry that looks like: &dquot;isdn_tty: call from XXX - YYY ignored&dquot;
(in order for this to work, you must of course already have the ISDN
drivers in your kernel and active).

<sect1> msn_config: How do I configure my MSN?
<p>
If your telephone number were 56789, then it would be configured as follows:
<itemize>
<item>Modem emulation: <tt>&dquot;AT&amp;e56789&dquot;</tt>
<item>Network interfaces: <tt>&dquot;isdnctrl msn interface 56789&dquot;</tt>
<item>For test calls to yourself add the area code (e.g. 01234):
<code>
&dquot;isdnctrl addphone interface in 123456789&dquot; (without leading zero)
&dquot;isdnctrl addphone interface out 0123456789&dquot; (with leading zero)
</code>
</itemize>
You may find national differences here (check section <ref id="countries">).

<sect1> msn_mindialin: How can I minimize usage of MSNs for digital data dialin?
<p>
i4l gives priority to net interfaces. Therefore, you can get away with only
one MSN when you set it up like this:
<enum>
<item>Set up net interfaces (sync ppp, rawip) for all users that will want to
use them (ipppd or rawip), with their incoming phone number (precondition is
that it is transmitted).
<item>Set up ttyI* for all other users (X.75, async ppp).
<item>Set option `secure on'.
</enum>
i4l gives priority to net interfaces. `secure on' ensures that only users
that have been set up will be connected to a net interface. Users that want
to choose between both will have to use different outgoing MSNs to call you.

<sect1> msn_onlyone: How can I use one MSN for everything?
<p>
In Germany, this is not an issue any more since you can get the first 10 MSN
for free, however minimizing MSN usage may still be very interesting for other
countries.

Digital data dialin can easily be distinguished from voice/analog modem
dialin by the 'Service Recognition' code (&dquot;digital, data&dquot;).

For the differentiation between net interfaces (ipppd, rawip) and ttyI*
(X.75) see last question.

To get voice/analog modem to work in parallel, use mgetty for the analog
modem. Mgetty can handle analog data calls, faxes, and even voice calls as
answering machine if the modem supports it. Configure it for 10 rings. If
you take the phone and hear a fax or modem, send mgetty a USR1 signal (kill
-USR1 mgetty-pid). If your phone socket is correctly wired, the modem will
take over the connection, cutting off the phone. If you have an ISDN PBX
then you can forward the call to a different analog port when you picked up
a fax/modem call.

If your analog modem can not handle voice calls, then you have to
choose since incoming voice calls can not be distinguished from analog
fax/data calls. Use either VBOX to take your voice calls as an answering
machine. Or forget about voice calls and set up your modem to handle only
faxes and/or analog data calls.

<sect1> msn_buendel: Can I have several NTBAs, all with the same MSN?
<p>
Yes, but you need the cooperation of your telecommunication company. They
can set up several BRIs in Point-to-point mode that have the same MSN. In
Germany it is called a bundled line (`Bündelanschluß').

<!-- Config for remote device
-->

<sect> remote: Configuration according to remote ISDN device
<label id="remote">

<!-- Config Win95
-->

<sect1> remote_w95: What do I have to watch out for to connect to Windows95?
<p>
VJ (i.e. header) compression should be turned off on both sides, at least for
the beginning (for more details on compression with ipppd see question
<ref id="syncppp_compression">). Windows95 is very touchy if this option is
rejected by isdn4linux.

<!-- Config Mac
-->

<sect1> remote_mac: I'd like to exchange data with a Macintosh (Leonardo card),
what do I or the Mac user have to watch out for?
<p>
Currently, the Leonardo protocol is not supported by i4l. When you call the
Mac, he should set the protocol to X.75 or HDLC. When he calls you, he must
explicitly set the protocol (e.g. by inserting an &dquot;X&dquot; for X.75) in
the called number.


<sect1> remote_macpap: A Macintosh with a Leonardo card tries to call in,
and wants to negotiate chap md5. How can I switch it to CHAP/PAP?
<p>
You can't. The user should use LeoPort (always included with the card) and
switch the CTB port to the ISDN card. Then with FreePPP 2.5v2
<tt><url url="http://www.rockstar.com"></tt> set the Leo as the modem and
configure FreePPP as usual. Then PAP/CHAP can be set.

<sect1> remote_cisco: How does isdn4linux work with a Cisco (HDLC) on the other side?
<p>
On the Cisco router the &dquot;keep alive&dquot; packets have to be turned off.
isdn4linux has to be configured with HDLC, transparent, with Cisco
encapsulation:
<code>
isdnctrl l2_prot &lt;interface&gt; hdlc
isdnctrl l3_prot &lt;interface&gt; trans
isdnctrl encap &lt;interface&gt; cisco-h
</code>

<sect1> remote_ispa: What settings does ISPA etc. (DOS, Windows) need to work with the 
standard settings of isdn4linux?
<p>
The following configurations are possible (these also apply to the
other drivers from H. Hanewinkel, i.e. CINDI, CANDI, WISPA...)
that can be found via <tt><url url="http://www.informatik.uni-bremen.de/&tilde;henker/dank"></tt>
<verb>
i4l side                             ISPA side
====================================================
isdnctrl l2_prot isdn0 hdlc           \
isdnctrl l3_prot isdn0 trans              -h0
isdnctrl encap   isdn0 rawip          /
----------------------------------------------------
isdnctrl l2_prot isdn0 hdlc           \
isdnctrl l3_prot isdn0 trans              -h1
isdnctrl encap   isdn0 uihdlc         /
----------------------------------------------------
isdnctrl l2_prot isdn0 x75i           \
isdnctrl l3_prot isdn0 trans              -l0
isdnctrl encap   isdn0 rawip          /
----------------------------------------------------
isdnctrl l2_prot isdn0 x75i           \
isdnctrl l3_prot isdn0 trans              -l1
isdnctrl encap   isdn0 uihdlc         /
---------------------------------------------------- 
</verb>
The parameter with the least problems is -h0.


<!-- ttyI* devices
-->

<sect> ttyI: Configuration of the ttyI* devices (`Modem emulation')

<sect1> ttyI_nomodem: Don´t the ttyI* devices emulate an analog modem?
<p>
No! The ttyI* devices just offer a similar communication interface, where
all commands are started with <em/AT/. This makes it easy to reuse software
that was written to communicate with a modem. <bf>Communication with a remote analog
modem is not possible via the ttyI* devices!</bf> The real communication
happens in digital, not analog form.

<sect1> ttyI_dev: Which devices should I use for calls out or calls in?
<p>
Only the ttyI* devices should be used. The cui* devices are created 
only for reasons of compatibility. Now that there is mgetty, there is not
reason to use the cui* devices any longer. If they are used, locking will
not work correctly (several programs could simultaneously attempt to use
the same device).

<sect1> ttyI_hdlc: How to I switch the modem emulation from X.75 to HDLC?  
<p>
With the option S14=3; for example &dquot;ATS13=3&dquot;.

<sect1> ttyI_uucp: How can I poll with Taylor-UUCP using isdn4linux?
<p>
As usual, the same as with serial interfaces. Simply use /dev/ttyI* as the
device, as the init string for the modem emulation you have to set the
correct MSN or EAZ with &dquot;AT&amp;Emsn/eaz&dquot;.

<sect1> ttyI_speed: What speed should I set for the ttyI* devices?
<p>
It doesn't matter. The driver internally always uses the full speed that
ISDN offers. This is also given in the connect string.


<!-- Trouble ttyI* devices
-->

<sect1> ttyI_nocarrier: When I dial with &dquot;ATD.....&dquot; I always
get a &dquot;NO CARRIER&dquot;.
<p>
Before dialing, you have to enter &dquot;AT&amp;E123456&dquot; (if 123456 is your
own MSN; with 1TR6 give the one-digit EAZ).


<sect1> ttyI_noincall: My ttyI* device/pppd does not recognize an incoming
call.
<p>
Probably you did not tell the modem emulation with <tt>AT&amp;E</tt> which
MSN to use. For example, use <tt>AT&amp;E123456</tt>; if your MSN is 123456.

<sect1> ttyI_callphone: Why can't I dial my telephone or fax from the ttyI*
devices?
<p>
You can. However, ISDN differentiates different services. All outgoing calls
with the ttyI* devices use the service &dquot;Digital Data&dquot;, which is
incompatible with telephone or fax, so the call never gets through.
Change the service recognition with the <tt>ATS18=1</tt> command to audio, then
you can dial your telephone or fax.

<sect1> ttyI_noconnect: I can't get a connection to my ISDN mailbox/BBS.
<p>
There are several possible protocol parameters. There is HDLC, there is
X.75 and there are several possible block sizes with X.75. You can tell
the modem emulation about the block size with <tt>AT&amp;</tt>. Mostly
used is a block size of 2048 byte: <tt>AT&amp;B2048</tt>.

<sect1> ttyI_forcehangup: My modem emulation hangs. How can I force my card to
hang up?
<p>
If there is really no process using your modem emulation any more, try:
<code>
cu -l /dev/ttyI0 dir
+++
ath0
&tilde;.
</code>
Before and after &dquot;+++&dquot; you have to wait for a second, otherwise the
modem emulation won't recognize it as the escape sequence (like a normal modem).
Watch out for processes that (with &dquot;ps -ax&dquot;) have something like
&dquot;I0&dquot; or &dquot;I1&dquot; in the second column, they have an ISDN
terminal as their controlling terminal. You may have to kill them with kill.

<sect1> ttyI_channelclosed: During a tty connection, I get a message from the kernel
&dquot;teles_writebuf: channel not open&dquot;. Then no more input is accepted
for this connection.
<p>
Can happen when the partner cannot handle the large frames from i4l and simply
closes the B channel during the transfer. Try making the frames smaller with
AT&amp;B512.

<sect1> ttyI_uucp: When I use UUCP with X.75, I always get transfer errors!
<p>
Andreas Gutzwiller <tt><htmlurl url="mailto:andy@hippo.proxyon.imp.com"
name="andy@hippo.proxyon.imp.com"></tt> wrote on 5 Dec 1996:
<quote>
I had to use the following settings, otherwise I only had errors.
&num; Prot
protocol-parameter g packet-size 512
protocol-parameter g short-packets y
protocol-parameter g window 7
protocol-parameter g remote-window 7
protocol-parameter v packet-size 512
Now with large packets I can get ca 7300 cps.
</quote>
Holger Burbach <tt><htmlurl url="mailto:holly@cthulhu.pfalz.de"
name="holly@cthulhu.pfalz.de"></tt> on 5 Feb 1997 had another
solution:
<quote>
I have several XP users who poll without any problems. I did
the following: First I set the send packet size for ttyI?
to 1024 (&dquot;AT&amp;B1024&dquot;) and then set the packet size for the
g protocol in UUCP:
protocol-parameter g packet-size 2048
protocol-parameter g remote-packet-size 0
As I said, it works fine..
</quote>




<!-- Config Async PPP
-->

<sect> asyncppp: Configuration Async PPP

<sect1> asyncppp_whichppp: pppd, ipppd, async PPP, sync PPP - what are they?
Which should I use?
<label id="asyncppp_whichppp">
<p>
<bf>async PPP</bf> is a character-based protocol which is usually used over
analog serial lines (async = asynchronous). You have to use the program
<tt/pppd/ for it, and use it with the ttyI* devices.

In contrast, <bf>Sync PPP</bf> is a bit-oriented protocol (sync = synchronous),
for which the original <tt/pppd/ cannot be used. Michael Hipp has written an
adapted version called <tt/ipppd/ which will use ipppd* net devices.

With i4l you can have both. It all depends on what your ISDN counterpart
supports. If it immediately begins to send frames, then you´ve probably reached
an sync PPP machine. If you can log in via same terminal screen, and then can
start ´pppd´, this can be an indication of async PPP.

Usually using <bf/sync PPP/ works fine, and it is slightly more efficient. To
take advantage of newer features of the <tt/pppd/, use <bf/async PPP/.

<sect1> asyncppp_config: How do I configure async PPP?
<p>
Just set up a normal pppd, but tell it to use one of the ttyI* devices,
e.g. /dev/ttyI0. You can set up several pppd´s with different configuration on
different ttyI* devices.
On problems also check out the section about the syncppp problems, since many
configuration problems are common for pppd (async PPP) and ipppd (sync PPP).

<sect1> asyncppp_logindelay: How can I reduce login delay?
<p>
You can write out a login session with (&dquot;Debug-Log&dquot;), and see which
options the other computer is refusing. Next time, configure ipppd
without these unused options. A further side effect is that such
unused options increase the redundance (e.g. when the other computer
has bugs and refuses the options incorrectly). To create a log file, 
see &dquot;How to I create a log for ipppd&dquot;.

<sect1> asyncppp_fast: How can I increase my transfer rates with PPP?
<p>
You can add more channels with MPPP (see the appropriate section).
For everyone for whom that's to expensive and who use <em>async PPP</em>,
there's a little trick. With the option &dquot;asyncmap 0&dquot; you can avoid
escaping all control characters (ASCII32). If the other side goes 
along with this, you can increase the transfer rate by about 12&percnt;.


<!-- Troubleshooting Async PPP
-->

<sect1> asyncppp_log: How can I get a log for pppd?
<p>
See this question for Sync PPP, it works the same way for pppd.

<sect1> asyncppp_suddendeath: Establishing the connection works fine, but pppd
crashes just after that (i.e. the first bytes gets through, but then everything
stops)
<p>
This is probably due to an incorrect block size on your side. Initialize your
ttyI* device with <tt/AT&amp;B512/ or even smaller block sizes.


<!-- Config Sync PPP
-->

<sect> syncppp: Sync PPP

<sect1> syncppp_whichppp: pppd, ipppd, syncPPP, asyncPPP .. what is they? Which
should I use?
<p>
See this question in the <em/asnyc PPP/; section: <ref id="asyncppp_whichppp">.


<sect1> syncppp_compile: How do I compile isdn4linux with syncPPP?
<p>
To compile the kernel with syncPPP included in ISDN4Linux, you have to answer
the appropriate questions with &dquot;yes&dquot;. Don't forget to load the
module slhc.o before isdn.o, if VJ compression is not compiled into the kernel
e.g. if you have no PPP and no CSLIP in the kernel. (Note that the use of VJ
is problematic and does not work reliably - however, the support should still
be included in the kernel, since there can otherwise be side effects.)

<sect1> syncppp_netinterface: How should I name my network interface?
<p>
The name of the network interface should <em>always</em> begin with
&dquot;ippp&dquot;, <em>not</em> with &dquot;syncppp&dquot; or
&dquot;isdn&dquot;; otherwise the communication with ipppd will not work
correctly.

<sect1> syncppp_config: How do I configure isdn4linux with syncPPP?
<p>
Synchronous PPP is simply another encapsulation for ISDN4Linux. This
encapsulation is called &dquot;syncppp&dquot;. Here is an example to
configure the link level device ippp0:
<code>
/sbin/isdnctrl addif ippp0
/sbin/isdnctrl encap ippp0 syncppp
</code>
All ippp* devices in use must be configured separately. Each ippp* device
should be assigned to its own IP address  (routing!). Several ippp* devices can
be assigned to a single MSN. Several callers can then simultaneously use this MSN.

To use these devices you need the program <tt/ipppd/, which you have to
configure. You have to start ipppd once after the modules are installed. ipppd
needs to be constantly running to allow dialout/dialin. It communicates with
the isdn4linux link level devices through <tt>/dev/ippp0</tt> to
<tt>/dev/ippp63</tt>. A single ipppd can handle all devices at once. If you
want two PPP connections at the same time, you need to bind ipppd to two
devices, etc. As a result, <tt/ipppd/ provides the network device
<tt>ippp0</tt>, which can be checked with ifconfig (even so it has the same
name, the network device <tt/ippp0/ is not to be confused with
<tt>/dev/ippp0</tt> which is used for communication between ipppd and link
level.

ipppd has an additional option: &dquot;useifip&dquot; uses the IP address
of the connected network interface (if it is not 0.0.0.0). (Even then, ipppd
tries to use the pointopoint address as the remote IP.) For the beginning,
disable all compression (lzs/stac, bsd, van jacobson), later you can try to
enable it (see question <ref id="syncppp_compression">).

You can find an example configuration in the file <tt>etc/rc.isdn.syncppp</tt>
in the isdn4kernel-util package.

<sect1> syncppp_busy: How can I tell if a connection is unsuccessful (busy)?
<p>
When giving the option ´defaultroute´, then you can wait a few seconds, then
check whether the default route exists. Another way, when giving option
<tt>useifip</tt> is to check whether you find entries like <tt>&dquot;Local IP:
x.y.z.a&dquot;</tt> and/or <tt>&dquot;Remote IP: x.y.z.a&dquot;</tt> in syslog.
In either case, the connection is up.

<sect1> syncppp_logindelay: How can I reduce login delay?
<p>
You can write out a login session with (&dquot;Debug-Log&dquot;), and see which
options the other computer is refusing. Next time, configure ipppd
without these unused options. A further side effect is that such
unused options increase the redundance (e.g. when the other computer
has bugs and refuses the options incorrectly). To create a log file, 
see &dquot;How to I create a log for ipppd&dquot;.

<sect1> syncppp_2configs: I want to talk to remote machines which needs different
configurations. The only way I found to do this is to kill the ipppd and start
a new one with another config to connect to the second machine.    
<p>
You must bind a network interface explicitly to an ippp device, where you 
can connect a (for this interface) individually configured ipppd. With the 
(unfortunately poorly documented) command
<code>
&dquot;isdnctrl pppbind interface Number&dquot;
</code>
you can link the interface interface to the device ipppNummer. You can 
release the link with &dquot;pppunbind&dquot;. 

<sect1> syncppp_pppbind: How does the (little-documented) &dquot;pppbind&dquot;
command in isdnctrl work?
<p>
You have to first know how ipppd gets its data. All data that come in
over the ISDN line is received by the network devices (these are 
set up with isdnctrl). Then the data given to one of the /dev/ippp*
devices - to one where a ipppd daemon is waiting for data.

To the network interfaces, all ipppd's appear to be able to handle the
just-received data - therefore it is normally impossible to predict
which ipppd will receive data from which network interface.

In practice, you usually install several ipppd's with differing 
configurations. Each of these should receive data <em>exclusively</em> 
from a certain network interface (that has also be specially configured).
The &dquot;pppdbind&dquot; command serves just this purpose. With:
<code>
&dquot;isdnctrl pppbind interface number&dquot;
</code>
attaches the interface interface to the device /dev/ipppnumber.

Example: To attach the interface &dquot;ippp5&dquot; to /dev/ippp2, the following
configuration should be used:
<code>
&dquot;isdnctrl pppbind ippp5 2&dquot;
</code>
Similarly, the command &dquot;pppunbind&dquot; will undo this attachment.

<sect1> syncppp_dynip: I want to use dynamic IP address assignment. How must I
configure the network device?
<p>
At least you must have a route, which forwards a packet to the ippp 
network interface to trigger dialing. A default route to the ippp interface 
will work. Now you must choose a dummy IP address for your interface. If for
some reason you can't set the default route to the ippp interface, you may 
take any address of the subnet from which you expect your dynamic IP number 
and set a 'network route' for this subnet to the ippp interface. To allow 
overriding of the dummy address you must call the ipppd with
the 'ipcp-accept-local' option. You must know how the ipppd gets the
addresses it has to configure. If you don't give any option, the ipppd
tries to negotiate the local host address!  With the option 'noipdefault'
it requests an address from the remote machine. With 'useifip' it gets the 
addresses from the net interface. You also can set the addresses in the 
option line with the a.b.c.d:e.f.g.h option. Note: the IP address of the 
remote machine must be configured locally, or the remote machine must send 
it in an IPCP request. If your side doesn't know the IP address after 
negotiation, it closes the connection! You must allow overriding of 
addresses with the 'ipcp-accept-*' options, if you have set your own or the 
remote address explicitly. Try these options, e.g.:
<code>
/sbin/ipppd :&dollar;REMOTE noipdefault /dev/ippp0
</code>
where REMOTE must be the address of the remote machine (the machine giving 
your address to you) 

<sect1> syncppp_ipx: How can I do IPX over ipppd?
<label id="syncppp_ipx">
<p>
Give the option <tt/+ipx-protocol/ to the ipppd.

<sect1> syncppp_faster: How can I increase my PPP data transfer rates?
<p>
You can establish more channels with MPPP (see the MPPP section). Another way
is to use compression, see question <ref id="syncppp_compression">.

<sect1> syncppp_compression: Which compressions can I use with ipppd?
<label id="syncppp_compression">
<p>
<em>Van Jacobson compression</em> (header compression) is in experimental state. It
works for some remote devices, but not for others. Check it out on your own
risk, to be sure disable it. <em>Lzs compression</em> (sometimes also called
<em>Stac compression</em>) works quite well. To enable it, some manual work has
to be done to add the code to the ipppd (see the isdn4k-util package).
<em>Bsd compression</em> also seems to work, but is in experimental stage. You
find it in the CVS tree.


<!-- Trouble ipppd
-->

<sect1> syncppp_strategy: I can't get a connect. How can I find out where the
problem is?
<p>
The output of ipppd is very helpful... (see next question: <ref id="syncppp_log">)
<itemize>
<item>Have a look at the error messages and see the following questions...
<item>Check whether you can find a few &dquot;LCP-conf-req SENT&dquot; messages
(less than ten) and then a &dquot;TERM-REF&dquot;.
<item>Check whether the ISDN card was configured properly. It seems the
computer doesn't dial (IRQ, IO, protocol wrong?)
<item>At least a few &dquot;RECV&dquot; messages: good! The card is dialing and
your dialin computer tries to communicate. Maybe the pap/chap authentication
doesn't work (see question <ref id="pap">). Check the ipppd
configuration!
<item>The message that ipppd was exited for some reason: not so good!
Check /var/log/messages and /var/adm/daemon. Could be a bug in ipppd.
<item>The error/cause E0010 is <bf/NOT/ an error! It is just the informal
message that the call has ended.
</itemize>

<sect1> syncppp_log: How can I get a log for ipppd?
<label id="syncppp_log">
<p>
For debugging purposes you can redirect the PPP log into a separate file.
Just edit /etc/syslog.conf and add the following line (caution: do NOT use
blanks or tabs):
<code>
daemon.*                      /var/log/ppp-log
</code>
then every information from PPP demon will be logged to /var/log/ppp-log.
Emil Stephan <tt><htmlurl url="mailto:ste@esqhen.su.eunet.de"
name="ste@esqhen.su.eunet.de"></tt> also wrote:
<verb>
Remove the comment sign in front of this line in /etc/syslog.conf:
&num;*.=debug                       /tmp/debug
After changing this file you can restart syslogd with &dquot;kill -1 pid of
syslogd&dquot;.
The output in /tmp/debug can be used to optimize the handshaking of
PPP options.
</verb>

<sect1> syncppp_nopppsupport: Starting ipppd I get the error message
&dquot;this systems lacks ppp support&dquot;.
<p>
Check whether the device &dquot;ippp0&dquot; exists (i.e. with the program &dquot;ifconfig&dquot;).
The ipppd *needs* this device with exactly *that* name. If it doesn't exist
one has to define it:
<code>
isdnctrl addif ippp0
isdnctrl encap ippp0 syncppp
... (see i4l documentation for more information) ...
</code>
Maybe you compiled ipppd with the source of another kernel that you are not
using...
See also the question &dquot;How should I name my network interface?&dquot;
under &dquot;Sync PPP&dquot; in the &dquot;Configuration&dquot; section.

<sect1> syncppp_nousabledevice: When I try to start ipppd it says &dquot;Can't find usable
ippp device&dquot;
<p>
This message occurs when the linklevel interface is told to dial out, but ipppd
is not running, or not available.

<sect1> syncppp_starterror: When I start ipppd, I only get error messages from
the i4l driver.
<p>
When ipppd is started, it calls functions that can trigger a network
packet (e.g. gethostbyname()). Without ipppd (since at this time, ipppd
it has not been fully started), this network access cannot be processed,
You should try to put the needed hostnames in the local /etc/hosts or
in some way define the name so that it can be resolved without having
the access the ISDN/ippp interface. 

<sect1> syncppp_framesdelayed: I get the message <tt>IP frames delayed</tt> -
but no connection.
<p>
Have you really dialed out? Check question <ref id="config_dialmode"> and your
configuration on the different dialmodes.

<sect1> syncppp_noroute: I cannot dial out with <tt>isdnctrl dial
ippp0</tt>. It seems as if the route to ipppd is missing although I <bf/did/
set it (<tt>network unreachable</tt>). With my old kernel 2.0 everything works
fine!
<label id="syncppp_noroute">
<p>
In the newer kernels you have to place <tt>route</tt> as the very last command
before the dialout command. Otherwise the kernel will delete the route.

<sect1> syncppp_nodefaultroute: After ipppd dials out my default route is gone.
<label id="syncppp_nodefaultroute">
<p>
It's the kernel's fault. Newer kernels (= 2.0) have some changes in the
routing. Workaround: install a script /etc/ppp/ip-up like this:
<code>
&num;!/bin/sh
/sbin/route add default ippp*
</code>
If you make your connections manually, can use something like this script:
<code>
/sbin/isdn
&num;! /bin/sh
case &dollar;1 in
on)
/sbin/isdnctrl dial ippp0       &num;  build up connection
sleep 5                         &num;  wait until line open
/sbin/route add default ippp0   &num;  set route
;;
off)
/sbin/isdnctrl hangup ippp0     &num;  hangup connection
/sbin/route del default         &num;  and delete route again
;;
*)
echo -e &dquot;\a Usage: 'isdn on' or 'isdn off'&dquot;
;;
esac
</code>

<sect1> syncppp_packettoolarge: I often get the error message
<tt>hscx_empty_fifo: incoming packet too large</tt>
<p>
Probably one of the compressions is activated (i4l can't handle those very
well). See also next question.
Another possible reason could be an IRQ problem - see question &dquot;Why should
I avoid IRQ 12 and 15 for my ISDN card?&dquot;.
Another problem can be `&num;' characters in your pap-secrets file. In this
case you have to surround user name and/or password with quotation marks
(depending on which one is affected).

<sect1> syncppp_slow: The connection with ipppd seems to work, but eventually it
crashes or is very slow.
<p>
It could be that some compression is activated (that i4l can't
handle properly). Common error: &dquot;-vj&dquot; has to be used *additionally*
to &dquot;-vjccomp&dquot; (to completely switch off the VJ compression) - the
example scripts coming with ipppd don't have that option included already.
Other compression modes (bsd, pccomp) can cause trouble, too. Therefore, you
should switch off all compression options (see also question
<ref id="syncppp_compression">). Also giving the option &dquot;noccp&dquot;
can help.

<sect1> syncppp_loadproblem: I only have problems with ipppd when the
connection is being heavily burdened. Then everything stops. What could be
causing this?
<p>
Sven Engelhardt <tt><htmlurl url="mailto:sven@sik.de"
name="sven@sik.de"></tt> wrote on 12 Dec 1996:
<quote>
We are an ISP here in Dresden and use Linux (among other systems)
for our access (with I4L as well as with external terminal adapters).
We have this problem mostly with Windows 95 and NT customers who
are using the &dquot;included&dquot; (modem network) software. It doesn't make
any difference whether the customer is dialing with async or sync PPP.
It also doesn't matter which modem emulation he is using on his side.
What they have in common is that the connection is made with Microsoft
modem adapter + Microsoft PPP (although a colleague recently told me
about a similar problem with a Macintosh customer).
Since it doesn't matter to PPP who is the server and who is the
client, ask your ISP what kind of hardware you are dialing into (we
have had no problems with Linux customers and Trumpet Winsock
users, therefore I suspect a bug in MS-PPP).
The following workaround usually works for us: (it's not a cure,
but helps to reduce the pain...)
* Reduce the Max MTU to 576 or even (296)
* Reduce the  DefaultRcvWindow to 2144
On the Windows 95 side these are 2 Registry entries; on the Linux
side you can set &dquot;mtu 576&dquot; and &dquot;mru 576&dquot; in the PPP options.
(see also:
</quote>
<tt><url url="http://www.windows95.com/connect/trouble.html"></tt>)
Erik Corry <tt><htmlurl url="mailto:ec@sign-tronic.dk"
name="ec@sign-tronic.dk"></tt> added on 16 Dec 1996:
<quote>
For me, neither PPP compression option nor mru/mtu 296 helped.
What did help was the AT command:
AT&amp;B512
that limits the sent packets to 512 bytes.
</quote>

<sect1> syncppp_mtu: My ipppd works, but I keep getting the message pppd(104): 
ioctl(SIOCSIFMTU): Invalid argument&dquot;?
<p>
If mtu is not set, then a default value is assumed - possibly &dquot;0&dquot;
(which of course cannot be correct). Add <tt>&dquot;mtu 1024&dquot;</tt> to
your ipppd options (1500 could also be ok). 

<sect1> syncppp_1stpacket: The first IP packet gets lost on automatic dialout
with dynamic IP address allocation.
<p>
There are some dialout problems in connection with syncPPP and dynamic IP
address allocation. In this case your IP address will change while packets
are waiting to be sent. All packets that should be sent before the change
in IP address have the wrong response ip address and will therefore never
receive an answer. Possible solutions:
<itemize>
<item>Dial out manually with &dquot;isdnctrl dial ippp*&dquot;
<item>Use diald to control when the connection goes up or down.
<item>Get a permanent IP address
<item>May be fixed in newer kernels.
</itemize>

<sect1> syncppp_droppacket: What does the message &dquot;No phone number, packet
dropped&dquot; mean?
<p>
Michael Engert <tt><htmlurl url="mailto:michi@bello.wor.de"
name="michi@bello.wor.de"></tt> wrote in Nov/Dec 1996:

That means that your computer has an IP packet from somewhat who was
logged on a few seconds before, but has since broken the connection.
Your computer tries to send this packet on and finds an appropriate 
route. But the interface isdn(0|1|...) can't reach the other computer,
since it has no telephone number to dial.

<sect1> syncppp_leadingzero: Why does my ipppd dial one too many zeros
(<tt>&dquot;ippp0: dialing 0 089XXXXXX...&dquot;</tt>)? I don't have any
extensions!
<p>
The first zero is not dialed. It only shows which channel is used for
dialing.

<sect1> syncppp_ethfake: My ISDN device is shown with HWaddr and IRQ=0 and
base address = 0 when I list it with ifconfig
<p>
The ISDN device fakes an Ethernet device. It ignores IRQ and baseaddr and
just needs the HWaddr for the Ethernet encapsulation.



<!-- Config Network
-->

<sect> lan: ISDN4Linux in a LAN

<sect1> lan_config: How can I set up Linux so that other computers in my LAN can
access the internet via my Linux computer?
<p>
There are several possibilities:
<enum>
<item>Your LAN is an official Class C net with IP addresses valid on the Internet.
This case is the easiest of configure. You give each network card on your
network one of these addresses and set a default route on the ISDN card that
goes to your provider.
<item>You'd only like to do http in Internet from your LAN. In this case you
can make up IP addresses for your LAN; the only official IP address is that for
your ISDN card. Then install a proxy server on your Linux router, and enter it
in all of your browsers. In this case you do not need a default route.
<item>From your LAN you only want to log in to your Linux ISDN router and FROM
THERE do your work on the Internet. This is even simpler, then you don't even
need a proxy server.
<item>Use ip masquerading. This is the most comfortable one to use, but more
difficult to set up. The Linux computer acts as a gateway. The trick is that it
hides the ip addresses of the LAN, by giving its own internet address as
response address. When receiving the response, it will forward it to the
correct computer on the LAN. You can also use masquerading with dynamic ip
addresses. If you don´t want to start the ISDN connection from the Linux
computer to your internet provider manually, then you can set up dial on demand
functionality (see section <ref id="dod">).
</enum>


<sect1> lan_modemserver: How can I allow the users in my LAN to dial out via
the ISDN card(s) in my Linux PC (like a modem server)?
<p>
On the Linux side use modemd, which is a very short perl script:
<code>
&num;!/usr/bin/perl
select((select(STDOUT), &dollar;| = 1)(&dollar;());
select((select(STDIN), &dollar;| = 1)(&dollar;());
exec &dquot;cu&dquot;,&dquot;-E&dquot;,&dquot;''&dquot;, &dquot;-l&dquot;, &dquot;&dollar;ARGV(0)&dquot;;
die &dquot;&dollar;0: Cannot exec cu: &dollar;!\n&dquot;;
</code>
It has to be started in inetd:
<code>
modem           20006/tcp       modemd  &num; Modem service via TCP
isdn            20007/tcp       modemd  &num; ISDN  service via TCP
</code>
Additionally, you need some software on your non-ISDN computer which emulates a
serial port, but redirects it via telnet to the Linux ISDN computer.
Some telnet clients allow this functionality (e.g. some uucicos).
If you generally want to offer all applications a kind of &dquot;remote COM
port&dquot;, then there is COMT for Windows (95), and
&dquot;telser.device&dquot; for Amigas. Disadvantage of COMT: it is only visible
to 16bit applications.

COMT may be found on Simtel or one of its mirror:
<tt><url url="ftp://ftp.funet.fi/pub/simtelnet/win3/inet/comt200.zip"></tt>


<sect> isdnlog: Isdnlog

<sect1> isdnlog_servicetype: Can I see the service type from an incoming call in the output
from isdnrep?
<p>
Andreas Kool <tt><htmlurl url="mailto:akool@Kool.f.EUnet.de"
name="akool@Kool.f.EUnet.de"></tt> wrote on 3 Dec 1996:

Indirectly in isdnrep, yes -- as soon as you enter an alias for the
decoded service types in your &dquot;isdnlog.conf&dquot; ...

<sect1> isdnlog_callerid1: Why don't I always receive from the German Telekom
the number of a caller (&dquot;Caller ID&dquot;)?
<p>
For data privacy reasons, telephone numbers from the analog network
are not transmitted unless the caller has explicitly allowed the Telekom 
to do so (costs nothing).

Those with an ISDN connection, on the other hand, must explicitly
deny permission for the Telekom to transmit the number, or apply to
be able to do this on a call-by-call basis (CLIR). Call-by-call
denial is free; call-by-call transmission costs extra. However, it
seems to be <em>very</em> difficult for the Telekom to configure this
correctly on the first try.  If you depend on the transmission of
Caller ID, you should check closely that everything is configured
correctly.

<sect1> isdnlog_callerid2: Do I receive the Caller ID from foreign calls
(German Telekom)?
<p>
Yes, with calls from countries that don't view Caller ID quite as strictly
as does Germany (e.g. USA, Canada).

<sect1> isdnlog_spoofcallerid: I've heard that actually two Caller IDs are
transmitted?
<p>
That's right, there's one that is &dquot;User-Provided, not
screened&dquot;, and the other is &dquot;Network-Provided&dquot; (from the
telephone company). As the name says, the first one is provided by the
user, whereas the second one is transmitted by the network.
Providing a caller ID is only possible for a PBX connected in
Point-to-point configuration with the feature &dquot;CLIP no
screening&dquot;.

<!-- Feature reversed card
-->

<sect1> isdnlog_betterlogging: Why doesn't isdnlog record the number dialed by
my other ISDN devices, since it records the charges?
<p>
Because the ISDN card, like all ISDN device, has separate lines for
sending and receiving (RX and TX lines). Isdnlog has to read data
from the receiving line to learn the number dialed. This isn't possible,
at least for the Teles cards, as Karsten Keil <tt><htmlurl url="mailto:keil@temic-ech.spacenet.de"
name="keil@temic-ech.spacenet.de"></tt> 
wrote on 12 Feb 1997:
<quote>
This is the case for all cards with 1 Siemens ISAX; it has (and needs)
only 1 sender and 1 receiver.
Theoretically, it's possible to read the entire D channel with just one
receiver (even with the ISAC); the D bits from the RX line are copied 
(somewhat delayed) to the TX line, over which the access control 
(collision recognition) of the SO bus takes place.
Unfortunately with the ISAC it's not possible to read the echo bits 
in TA mode from a register.
</quote>
See the next questions for a possible solution.

<sect1> isdnlog_reversedcard: How can I get isdnlog to also show the telephone
numbers for other ISDN devices?
<p>
There are two possibilities. First, the German Telekom offers the service
COLP (Connected Line Identification Presentation, ca. DM 10 per month per
basic line) that returns all data sent. This can then be read by isdnlog
(=2.52) from the TX line

Alternatively, the next version of isdnlog (currently 2.52) will offer
the possibility to work with a second &dquot;re-poled&dquot; Teles card, i.e. the 
RX line is connected to the TX connection of the card. The RX line of the
card should not be connected to any line! Because of this setup, the Teles
card cannot be used for anything else. The whole thing looks something like
this:
<verb>
      3 -- RX+ 2a ---------------\
ISDN  4 -- TX+ 1a -- open         ------------  ISDN
bus   5 -- TX- 1b -- open         ------------  card
      6 -- RX- 2b ---------------/ 
</verb>
A third (theoretical) possibility exists for those who have their own
PBX to which the other devices are connected. If the PBX can protocol
all outgoing calls, this can be read (usually over a serial port).

There is a reason why isdnlog has not support this until now. To evaluate
this data, isdnlog has to be able to access the date immediately after
the RELEASE COMPLETE, before any new data is sent on the D channel. The
PBXs tested up to now have all been too slow (in particular the widely
used ISTEC). The only possibility is to combine the data afterwards. But
then there are problems with synchronizing the different times. Whoever
want to attempt to do this is welcome (I'll make the logs from my
Ackermann Euracom available - Matthias Heßler <tt><htmlurl url="mailto:hessler@wi-inf.uni-essen.de"
name="hessler@wi-inf.uni-essen.de"></tt>).

<!-- isdnlog Features
-->

<sect1> isdnlog_rategraphic: How can I display the data transfer rates graphically?
<p>
You can use &dquot;xisdnload&dquot;. Clemens Perz <tt><htmlurl url="mailto:listperz@gwsnet.ttt.de"
name="listperz@gwsnet.ttt.de"></tt> on 6 Feb 1997
knew of another possibility:

On Sunsite I found a little tool for the console called netload, and
apapted it for the ISDN interfaces. With it you can quite easily see
the current traffic on the line. It can be found at:

<tt><url url="ftp://ftp.region.trier.de/pub/unix/linux/sources/network/isdn/netload-0.92.isdn.tar.gz"></tt>

Simply start with netload isdnxx


<sect> Audio
<p>
(Most of the answers you will find here are taken from the vbox manual by
Matthias Hessler <tt><htmlurl url="mailto:hessler@wi-inf.uni-essen.de"
name="hessler@wi-inf.uni-essen.de"></tt> and
Bernhard Hailer <tt><htmlurl url="mailto:dl4mhk@lrz.uni-muenchen.de"
name="dl4mhk@lrz.uni-muenchen.de"></tt>; you can get the manual at:

<tt><url url="http://www.lrz-muenchen.de/&tilde;ui161ab/www/isdn/"></tt>

- click on &dquot;Audio!&dquot; (still in German we're afraid - sorry...)
They are currently outdated, but may give you a few hints?

<sect1> audio_format: What is the format of the audio messages (.msg) vbox plays when it
answers a call?
<p>
You can get the format from the messages with rmdgetheader. The samples
messages in the packages are recorded using format 4 (the latest
Zyxel-Compression)


<sect1> audio_recordmsg: How can I record my own messages for vboxgetty?
<label id="audio_recordmsg">
<p>
First call yourself on the number you configured vboxgetty to answer and
leave a message. Then rename the message to *.msg (standard.msg for the
main answering message) and copy it to the directory where all the
messages are kept (usually /var/spool/vbox/user/messages where user is
the user for which vboxgetty is configured).
You can also record a message using a microphone and the soundcard.

<sect1> audio_play: How can I play audio messages locally using /dev/audio?
<p>
This is best achieved with vbox using format 6 (uLaw - must be compiled
in). You can then easily play the messages using:
<code>
cat xxx  /dev/audio
</code>
where xxx is the message-file.

<sect1> audio_convertto: How can I convert audio messages which where recorded by
vbox to other formats (i.e. from uLaw to WAV)?
<p>
The standard tool for converting all sound formats is SOX. SOX is
available as source code for both UNIX and DOS. You can get it at:

<tt><url url="http://www.powerweb.de/mpeg/util/msdos/sox10c.zip"></tt>

(including sources that compile under Linux).

<sect1> audio_convertfrom: How can I format WAV for uLaw (for my vbox
announcement message)?
<p>
We receive the following tip form Christian Stueble 
<tt><htmlurl url="mailto:stueble@ls6.informatik.uni-dortmund.de"
name="stueble@ls6.informatik.uni-dortmund.de"></tt> on 15 Jan 1997:

For me, the following (somewhat indirect) method works:   
<code>
sox file.wav -r 8000 file.ul rate
rmdcatheader -u file.ul  file.msg
cat file.ul  file.msg
</code>
It could be that you have to give different parameters to sox.
As a first test you can try file.msg  /dev/audio, you should
be able to hear something.


<!-- Audio Troubleshooting
-->

<sect1> audio_noanswer: My vboxgetty does not answer any incoming calls.
<p>
vboxgetty needs &dquot;.vboxrc&dquot; in the home directory of the user for which
vboxgetty is configured. The number of rings is taken from this file.

<sect1> audio_nocat: If vboxgetty has recorded a message in a format which can
not be played using &dquot;cat xxx/dev/audio&dquot; how can I still hear the
message?
<p>
Vboxgetty can play all formats. You can copy the message as the
standard message (standard.msg in the messages directory) and call
yourself, the message will be played then. (Don't forget to copy back the
original message when you are done :-) ). See question <ref id="audio_recordmsg">.

<sect1> audio_earlyrecording: At the beginning of a message recorded by vboxgetty,
there's often a part of my own announcement?
<p>
This is a known bug that occurs when switching between the playing of
the announcement and recording the message. Up to now there is no
known workaround.



<sect> chargeint: Chargeint

<!-- Feature Chargeint
-->

<sect1> chargeint_whatis: What does Chargeint?
<p>
Chargeint is a way to reduce your costs when you have charges based on your
<bf/time online/, and the interval between two charges (the Charge Interval) is
relatively large (e.g. per minute).

Chargeint only hangs up two seconds before the end of a charge unit. isdnlog
can be used to set the length of the charge unit (i.e. Charge Interval)
according to the time of day and the date.

<sect1> chargeint_config: How should I configure Chargeint?
<p>
You can set the length of a charge unit manually via the isdnctrl parameter
<tt/chargeset/, or set up isdnlog to do this automatically for you:
<enum>
<item>Set up isdnlog, so that it has all the information about your location
and your telephone company (so that it knows your rates).
<item>Start isdnlog with the options <tt>-h0</tt> and <tt>-w</tt>.
<item>Set your huptimeout as you like (idle time needed before i4l will
consider a hangup). E.g.:
<code>
/sbin/isdnctrl huptimeout ippp0 5
</code>
Then i4l will hang up 2 seconds before the end of your charge unit, if the 5
seconds before (huptimeout) no activity has happened on the line.
</enum>

<sect1> chargeint_whennot: When does it <bf/not/ make sense to use the
chargeint?
<p>
<enum>
<item>It does not make sense to use Chargeint when you are charged <bf/per data
volume/, or per <bf/flat fee/. Chargeint can only reduce your costs when you
are charged <bf/per time online/.
<item>Also it makes no sense if you are charged in small units (e.g. per second
rather than per minute).
<item>Chargeint may or may not make sense when every new dialup costs you fixed
amount on top of the variable charges (depending on the rates).
<item>There are problems when the ip address is assigned dynamically. A broken
connection cannot simply be restarted (since the IP address has changed). The
interrupted FTP, telnet or WWW connection must then be newly established.
</enum>

<sect1> chargeint_correcttime: How can I be sure that the chargeint patch is
using the correct time?
<p>
It's best to synchronize the clock in your own computer with that of the
switching station by calling isdnlog with option <tt>-t2</tt>.

<sect1> chargeint_nohangup: The connection doesn't end with timeout.
<p>
Chargeint will only hangup if there was no activity on the line. Possibly your
service provider uses a router (e.g. Cisco) which sends a &dquot;keep
alive&dquot; packets every ten seconds. If the Cisco doesn't get an answer for
its keep alive packets then it will stop routing. This normally happens after
the 4. or 5. keep alive packet. The best solution is to tell the provider not
to use keep alive packets (<tt>&dquot;no keepalive&dquot;</tt> in the Cisco
configuration).

It could also be that it's not the keep alive packets that are keeping the 
connection open, but rather OSPF routing updates. The sending of these
updates can only be switched off on the Cisco. You can configure
&dquot;snapshot server&dquot; on the BRI interface. That means it will
send out routing updates only when they are received through this interface.



<sect> dialin: Configuration of a Dial-In Server

<!-- Config Dialin Server
-->

<sect1> dialin_config: How can I enable others to login via ISDN?
<p>
The same way as via a normal serial port. Start a getty (mgetty from Gert
Doering is highly recommended) on one of the ISDN devices with modem 
emulation (/dev/ttyI*). The entry in /etc/inittab looks like this:
<code>
I0:56:respawn:/usr/local/sbin/mgetty ttyI0
I1:56:respawn:/usr/local/sbin/mgetty ttyI1
</code>
The init string needs to be entered in the <tt>mgetty.config</tt>, since
mgetty needs to know which MSN or EAZ to listen to. For example, if your MSN is
123456:
<code>
port ttyI0
modem-type data
speed 38400
init-chat &dquot;&dquot; ATZ OK AT&amp;E123456 OK AT&amp;B512 OK
</code>
For X.75 the block size was set to 512 bytes.
Alternatively you can enter the entire configuration onto a single line
in /etc/inittab (here printed on two lines!):
<code>
i0:45:respawn:/sbin/mgetty -D -m '&dquot;&dquot; ATZ OK AT&amp;E123456 OK
AT&amp;B512 OK' -s 38400 ttyI0
</code>
The most elegant way is to use iprofd. This daemon takes advantage of
the <tt>AT&amp;W0</tt> command in the i4l modem emulation. You start iprofd
with a path as parameter, e.g. &dquot;iprofd /etc/i4lprofile&dquot;
Then with minicom or another terminal program, open an ISDN tty
device and enter the necessary AT commander by hand. 
When finished, enter the command AT&amp;W0, then the kernel notifies iprofd 
to write the current configuration to the file. From now on it is enough
to start iprofd in you isdn init script, and to initialize the appropriate
ISDN tty devices with ATZ

<sect1> dialin_manyparallel: How can I allow several people to call in to me at
the same time?
<p>
You have to configure exactly as many gettys or network interfaces as the
number of people allowed to call in at one time. These gettys or network
interfaces can be set to the same MSN, since several people can be 
connected to a MSN at the same time (as long as there are B channels free).
However, not more than one getty can be assigned to a single ttyI* device. 

<sect1> dialin_hdlc: Someone would like to dial in to my mgetty with HDLC. Is
ttyI1 correct, or do I have to start with ttyI0?  
<p>
No, it doesn't matter. It also has nothing to do with the number of the
B channel (0 or 1). You just have to activate HDLC in the init string 
(ATS14=3).

<sect1> dialin_autoppp: Is it possible with mgetty to automatically start pppd when LCP frames
are received?
<p>
Yes, it is. This feature is called `AutoPPP'. See the configuration for
mgetty.

<sect1> dialin_passwd: How can I have (i)pppd check passwords from /etc/passwd
instead of /etc/ppp/pap-secrets when someone dials in?
<p>
ipppd needs to be started with the options &dquot;login&dquot; and
&dquot;auth&dquot;. In /etc/ppp/pap-secrets, each user must have the
following line to allow only certain users:
<code>
login-name * &dquot;&dquot; *
</code>
To allow all users simply:
<code>
* * &dquot;&dquot; *
</code>
The latter can also be achieved when the file pap-secrets does not
exist.


<sect> leased: Leased lines 

<!-- Config Leased line/D64S
-->

<sect1> leased_nosignal: How does establishing and ending a connection work
with D64S without signaling?
<p>
The data are simply sent out! Other than a ping, there is no way to find out
whether the D64S or 2MB line is up or not. Only S01 or S02 lines have a D
channel and have something to use with signaling, however the best
known solutions also use this 16kb for data transfers to get 144kb
instead of 128kb (i4l can only to 128kb).

<sect1> leased_hisaxconfig: With i4l, how do I configure my card on a D64 leased
line?
<p>
A later version of the new HiSax driver supports D64. Configuration is normal
with the following specialities. HiSax has to be run in leased mode:
<code>
/sbin/telesctrl HiSax 5 0
</code>
in case HiSax was loaded with &dquot;id=HiSax&dquot;. Additionally to the normal
configuration, the following commands are important:
<code>
&num; bind interface on first BChannel (,1 for 2nd)
/sbin/isdnctrl bind HiSax,0
/sbin/isdnctrl eaz isdn0 1
/sbin/isdnctrl addphone isdn0 out 2
/sbin/isdnctrl addphone isdn0 in  3
</code>
if &dquot;isdn0&dquot; was used as interface name. The interface has to be set to
&dquot;up&dquot; and a route associated with it. See the readme´s in the HiSax
package.

<sect1> leased_splitline: With ISDN, can I use one channel as a leased line and
other as a dialup line?
<p>
Yes, you can. But you have to make sure that you use the correct channel!


<!-- Config/Feature MPPP, raw bundling
-->

<sect> 2channel: Channel bundling (MPPP, raw bundling)

<sect1> 2channel_whatis: What is channel bundling and how can I use it?
<p>
Channel bundling is currently supported by isdn4Linux in two variations:
<itemize>
<item><bf>Raw Bundling</bf> (configuration of so-called slave channels)
<item><bf>MPPP</bf> (based on syncPPP)
</itemize>
Both variations have their own advantages and disadvantages. See the following
questions.

<sect1> 2channel_raw: What is raw bundling?
<p>
Raw bundling works similarly to raw IP, only with several channels.
Therefore, it has the theoretical advantages and disadvantages of 
raw IP. Raw bundling requires a network interface for each channel 
that is used. One network interface, the so-called master interface,
controls the establishment and breaking of connections. For each 
further channel, an additional so-called slave interface is configured, 
that is automatically switched on by the master interface.

<sect1> 2channel_rawconfig: How do I configure raw bundling?
<p>
The master interface is created as usual with 
<code>
isdnctrl addif master interface
</code>
and configured. For all required slave channels, slave interfaces 
are created with the command:
<code>
isdnctrl addslave master interface slave interface
</code>
and configured as usual (e.g. &dquot;isdnctrl sdelay slave interface delay&dquot;).

<sect1> 2channel_rawgoodbad: What are the advantages and disadvantages of raw
bundling?
<p>
Raw bundling has all the advantages and disadvantages of raw IP.
Compared to MPPP, raw bundling has the advantage that isdn4linux
itself can open and close the needed slave channels. Unfortunately
raw bundling still has problems with transfer rates. See the further
questions below.

<sect1> 2channel_mppp: What is MPPP?
<p>
MPPP or MP or MPP (Warning: MP is also an acronym for 'Multi Processor')
stands for Multi Point to Point and means bundling of several channels to
one logical stream. It's a variation of the normal syncPPP. Accordingly, it
inherits all its advantages and disadvantages. Just for your information: ipppd
does MPPP according to RFC 1717, instead of the newer RFC 1990 (MLP).

In contrast to raw bundling only one net interface is needed as interface
to the ipppd, since the ipppd handles all its channels by itself. Incoming
data is distributed round-robin by the ipppd on all available channels.
These channels do not necessarily have to be ISDN channels. In theory,
modem connections could be mixed with ISDN channels. However, here we only
cover ISDN channels.

<sect1> 2channel_mpppconfig: How do I configure MPPP?
<p>
First you define a (normal) interface for ipppd (e.g. &dquot;isdnctrl addif
ippp0&dquot;, etc). To enable MPPP negotiation you must call the ipppd with
the &dquot;+mp&dquot; option. You must also configure a slave device for every
additional channel (see the i4l manual for more). To use channel bundling
you must first activate the 'master' or initial call. Now you can add the
slave channels with the command:
<code>
isdnctrl addlink device
</code>
and close them with the command:
<code>
isdnctrl removelink ippp0
</code>
This is different to other encapsulations of isdn4linux!

With syncPPP, there is no automatic activation of slave devices, they have to
be added and removed. However, there is the program <tt>ibod</tt> available,
which can do this automatically. Have a look at:
<url url="http://www.compound.se/ibod.html">

In the file etc/rc.isdn.syncppp.MPPP in the isdn4k-utils package you
may find a sample script (unfortunately missing in some i4l version).

<sect1> 2channel_mpppgoodbad: What are the advantages and disadvantages of MPPP?
<p>
A disadvantage is that the slave channel has to be activated 
&dquot;manually&dquot;. ipppd cannot by itself turn the slave channel on and
off as it needs to. The normal automatic functions of ipppd are 
either unreliable (auto hangup) don't work at all (auto dial).
This is not true for the other encapsulations. The transfers
rates are very good (ca. 30 KB/s with 4 channels).

<sect1> 2channel_mpppcompile: I tried MPPP but it doesn't work. The ipppd
writes in the debug log something like:
&dquot; ...  rcvd (0)(proto=0x3d) c0 00 00 00 80 fd 01 01 00 0a ...
sent (0)(LCP ProtRej id=0x2 00 3d c0 00 00 00 80 fd 01 ...&dquot;
<p>
You forgot to compile MPPP/RFC1717 support into the ISDN Subsystem.
Recompile with this option enabled.



<!-- Troubleshooting Strategy
-->

<sect> trouble: Troubleshooting


<sect1> trouble_strategy: My isdn4linux doesn't work! How do I best go about
finding the problem?
<p>
The following steps are recommended:
<enum>
<item>Check everything is working when booting.
Are there unusual error messages in /var/log/messages?
Are all programs active that should be started at boot (check with
ps, or fuser /dev/xxx)? HiSax won't start if something isn't right.
The old Teles driver, on the other hand, will appear to start even if
it is not working. See the questions under Troubleshooting Teles.
<item>Try calling with a telephone. The number should be shown in
/var/log/messages. Otherwise, perhaps the driver was incorrectly 
started?!
<item>As a next step we´ll try to get the telephone or fax to ring by dialing
ourself using a ttyI device with minicom. First we have to change the service
recognition with the <tt>ATS18=1</tt> command to audio. Now you can get the
telephone to ring by dialing <tt>ATDxxxxxx</tt>, where xxxxxx is your own MSN.
<item>Next we try to transmit data via ISDN. Open 2 different consoles as root,
and on each run &dquot;minicom -s&dquot;... in the first set &dquot;Serial Port
Setup Serial Device&dquot; to <tt>/dev/ttyI0</tt>, and the other to
<tt>/dev/ttyI1</tt>. Then choose &dquot;Exit&dquot; and start the modem
emulation with &dquot;ATZ&dquot; and &dquot;AT&amp;Exxxxxx&dquot; (where xxxxxx
is your own MSN without the area code). Then you can start. On the first
console you can dial your own number with ATDxxxxxx. On the second console you
should now see &dquot;CALLER NUMBER: xxxxxxx&dquot; and
&dquot;RING&dquot;. Accept the call on the second console with
&dquot;ATA&dquot;, and you should then see the message &dquot;CONNECT
64000/X.75&dquot; on both consoles. You can then send characters to the other
console by typing (to see the characters on your own console, turn on local echo).
<item>Next, try calling a known ISDN BBS. If you don't know of any, try 
Gernot (see &dquot;Are there sites that offer guest access where I can test my
isdn4linux setup?&dquot;). If you have problems with the modem emulation, see
&dquot;Troubleshooting Modem Emulation&dquot;
<item>Fifth, try configuring the network interface or ipppd. Experience shows 
that they cause beginners (and not only beginners!) the most problems.
To make things easier and you're happy with asyncPPP (to see what 
asyncPPP means, see the question &dquot;pppd, ipppd, syncPPP, asyncPPP - 
what is that? What should I use?&dquot;), you can use the normal pppd with
modem emulation (i.e. /dev/ttyI*). 
<item>Ensure that you set up your authentication configuration properly (see
questions in section <ref id="pap">.
</enum>      
Otherwise, it is highly recommended that use an example script form
the HowTo (see the question &dquot;Where can I find scripts and other
information on configuring i4l?&dquot;). For testing you can try your own
provider or of the guest accounts (see &dquot;Are there sites that offer
guest access where I can test my isdn4linux setup?&dquot;).  The latter
have the advantage of being able to see the log files as well as a
stable, working configuration. For example, if accessing via ipppd
doesn't work, you can log in via modem or modem emulation to find
out what happened on the other side. Not all providers are so
cooperative.... :-)

<sect1> trouble_notelrings: Neither my telephone nor my fax machine ring when I
call them with isdn4linux?
<p>
Isdn4linux sets &dquot;digital data&dquot; as it's own service when it calls out.
The switching station will not route such calls to analog devices like
a telephone or a fax machine.


<sect1> trouble_boot: How can I tell whether my ISDN card has been corrected
recognized?
<p>
<enum>
<item>Check for error messages in the boot messages (you can review them at any
time with the command <tt/dmesg/.

<item>For the HiSax driver: During booting a message <tt>kernel: HSCX version
A:5 B:5</tt> and <tt>kernel: channels 2</tt> should appear. <tt>A:4 B:4</tt> is
also okay. Other values (in particular <tt>A:??? B:???</tt>) mean the card is not
recognized correctly.
HiSax is only loaded if the hardware can be found and the appropriate
interrupts can be generated. This means the card is installed correctly in the
computer, and there are no hardware conflicts. It does not mean that everything
will work (e.g. twisted cables, broken cables, terminators).

<item>Check that the interrupts are registered correctly. Check with
<code>
cat /proc/interrupts
</code>
The following entry indicates that the card is configured on interrupt 11, and
so far has received 3 interrupts:
<verb>
11:        3 + hisax
</verb>
When you call yourself, the number of received interrupts should increase.

<item>Check the io ports with
<code>
cat /proc/ioports
</code>
</enum>

<sect1> trouble_guestaccess: Are there sites that offer guest access where I
can test my isdn4linux setup?
<label id="trouble_guestaccess">
<p>
The following information is quite old. Please tell me if you find out that the
guest sites are not available any more:

The following sites offer guest access for modem emulation or IP:
<itemize>
<item>Eberhard Moenkeberg <tt><htmlurl url="mailto:emoenke@gwdg.de"
name="emoenke@gwdg.de"></tt>:
<itemize>
<item>Welcome to Linux at eberhard.moenkeberg.de (LAN, 192.168.99.1).
Under ++49-551-7704103, ISDN NetCalls (HDLC-trans-rawip)
for 192.168.99.1 get accepted. You should come as 192.168.*.*
because sometimes my &dquot;default&dquot; route is not your way.
/ftp is exported for NFS; try &dquot;showmount -e&dquot;.
You can login as &dquot;guest&dquot; without password.
FTP as &dquot;gast&dquot; with password &dquot;gast&dquot; avoids the
restricted shell.
<item>Under ++49-551-7704102, a 28800 bps modem and a Creatix ISDN 
card (HDLC only, not X.75) are listening for logins.
<item>With the net setup from
<tt><url url="ftp://ftp.gwdg.de/pub/linux/isdn/isdn4linux-gwdg/rc.isdn-Beispiel"></tt>
you can test NetCall at 551-7704103 (works as is within Germany,
from outside Germany you just have to change the number).
</itemize>

<item>Gernot Zander <tt><htmlurl url="mailto:hifi@scorpio.in-berlin.de"
name="hifi@scorpio.in-berlin.de"></tt>:
<quote>
There's a &dquot;gast&dquot; at +49 30 67 19 81 01 (X.75, mgetty). There's the 
stones-html-page with pics in postscript to test downloading. Whoever
needs a target to call can use it. At ...81 03 there's a getty with
HDLC. As guest you enter a kind of BBS and can read some news.
</quote>
</itemize>

<sect1> trouble_unload: I can't unload my ISDN modules (&dquot;isdn: Device or
resource busy&dquot;), even so I closed all ISDN applications?
<p>
In this case &dquot;fuser -v /dev/isdn* /dev/ippp* /dev/cui* /dev/ttyI*&dquot;
is very helpful. This helpful program shows, which processes are using those
devices.
<itemize>
<item>Is some program still using an ISDN device?
<item>Did you remove all getty's? (They may have restarted automatically)
<item>Are isdnlog, imon, iprofd, etc., still running?
<item>Maybe there is still a route on your net interface and it's not yet
deleted with &dquot;route del xxx&dquot;?
<item>Maybe the net interface wasn't put down. This can easily happen when
killing ipppd. It does not react to signal 15 and has to be killed with
&dquot;kill -9 ipppd pid&dquot;. Then the net interface is left
&dquot;up&dquot;.
</itemize>
Sporadic errors of this type can be fixed by inserting sleep commands
between the unloading commands.
As a very, very last resort, there are two secret telesctrl commands to adjust
the module counter:
<code>
telesctrl id 3 1  --- dec module_count
telesctrl id 4 1  --- inc module_count
</code>
Please use with appropriate caution and on your own risk!


<!-- Trouble locate crash
-->
<sect1> trouble_locatecrash: My isdn driver crashes my machine! Since I've
configured it as a module, the addresses change each time it's loaded. How can
I find out where the driver is crashing?
<p>
The driver should be loaded with the command &dquot;insmod -m&dquot;. The output
has to be transformed somewhat to be a form similar to System.map. You can do
it like this:
<code>
insmod -m isdn.o | sort | sed -e 's/   / T /g' |
                   egrep '.* T (a-z,A-Z,_)+'  /etc/isdn/isdn.map
cat /System.map /etc/isdn/isdn.map  /iSystem.map
</code>
(The line ending with &dquot;|&dquot; has to have the following text on
the same line!) iSystem.map should then be used instead of System.map for
finding the error.


<!-- Trouble/Config Finetuning
-->
<sect1> trouble_lotsdebug: My hard disk becomes very active when isdn4linux run. How can
I turn this off?
<p>
Check whether the reason for the hard disk activity is caused by the amount of
messages written into the logfile. If this is the case, you can reduce the
output by:
<code>isdnctrl verbose 0
</code>
and/or by removing the &dquot;debug&dquot; option for ipppd.


<sect1> trouble_outofbuffers: I get messages like &dquot;HSCX RME out of
buffers&dquot;, &dquot;HSCX RFP out of buffers&dquot;, &dquot;HSCX B EXIR
10&dquot; in the syslog?
<p>
These errors happen when i4l is not able to process its buffers fast
enough. They are often caused by bad sound cards or their drivers when
they disable the interrupts too long! It may also happen on old hardware
(happened to the author of this FAQ when using <tt/vbox/ on an old 386-25 with
only 4MB RAM). You may be able to work around it by increasing the number and
size of the buffers. Check the source code header files for definitions like:
<code>
&num;define HSCX_RBUF_ORDER 1 
&num;define HSCX_RBUF_BPPS 2 
&num;define HSCX_RBUF_MAXPAGES 3 
</code>
The first two influence the size, the last one the maximum number of buffers.

<sect1> trouble_noresetinit: After a soft reset, my card does not initialize
correctly.
<p>
After you stopped your system with the <tt/reboot/ command or with
<tt/Ctrl-Alt-Del/, press the reset button (=hard reset). Sometimes the card
needs to receive a hardware signal to reinitialize properly.


<sect1> trouble_xosview: xosview doesn't show any network activity since
installing i4l.
<p>
Peter Hettkamp <tt><htmlurl url="mailto:Peter.Hettkamp@kassel.netsurf.de"
name="Peter.Hettkamp@kassel.netsurf.de"></tt> wrote:
<quote>
xosview reacts, at least for me with version 1.4, to the IP accounting
in the kernel. So, configure, if necessary build a new kernel, then 
couple with:
ipfwadm -A -a -S your-ip-address-here -D 0.0.0.0/0
ipfwadm -A -a -D your-ip-address-here -S 0.0.0.0/0
(I don't know who it works with variable IP addresses. I have a fixed
address.)
</quote>

<sect1> trouble_unknownhost: When I for example from a W95 box call up a page
with Netscape, I only get the answer &dquot;unknown host&dquot;.
<p>
What is entered on the &dquot;Win95 box&dquot; for the name server? As long as the 
router has no name server of its own, then the provider's name server 
of course has to be entered on all computers on the LAN.

<sect1> trouble_noroute: Addresses are now found, but now I get &dquot;no route
to host&dquot;.
<p>
Please check:
<itemize>
<item>Is the Linux computer entered as the gateway? (Some 'operating systems'
have to be restarted before changes to the networking take effect)?
<item>Does the router have a default route to the prepared interface to the
provide (e.g. ippp0 with syncPPP or sl0 for diald (even when the real
connection is over ppp0, diald uses a slip interface as a &dquot;doorknob&dquot;)
<item>Does the provider require the use of proxies? Then the addresses  
of the proxies have to the entered in the appropriate clients on the LAN
computers
<item>Maybe your route was removed when using syncppp? Check the questions
<ref id="syncppp_noroute"> and <ref id="syncppp_nodefaultroute">.
</itemize>

<sect1> trouble_nolocalnet: After booting, my local network can no longer be
reached. I use the network interface ippp0 with ifconfig 0.0.0.0; the default
route points to ippp0.
<p>
Wolfgang Barth wrote on 5 Jan 1997:
<quote>
I've noticed that after the first connection via ippp0 that the local
network can again be reached. Then the address 0.0.0.0 is no longer
listed in ifconfig for ippp0, but instead the address assigned from
the pool by the PPP partner. 
This was already discussed in de.comp.os.linux.networking, along
this possible solution: 
Simply set ippp0 to a dummy IP number from the pool. Then the 
local network will have problems after booting, even with the 
default route, and the IP number in ifconfig will be overwritten
anyway.
</quote>


<!-- Trouble Authentication
-->
<sect> pap: Authentication Problems (especially with PAP)
<label id="pap">

<sect1> pap_optionauth: When dialing out, I get the message &dquot;pppd: peer
authentication required but no authentication files accessible.&dquot;
What does this mean?
<p>
Most likely the option &dquot;auth&dquot; was set by mistake. Then the
<em>other</em> side is required to be authorized.

<sect1> pap_requestauth: I cannot establish a connection -  it's rejected by the
other side. In the log file I find a message that's something like: &dquot;sent (0)
(LCP ConfReq id=0x1 mru 1500 auth pap magic 0xcd12e9c4&dquot;
<p>
Like in the last question, an option was been set that requires the
<em>other</em> side to be authorized. These options shouldn't be set.
Possible candidates are: &dquot;+pap&dquot; as well as &dquot;+chap&dquot;.

<sect1> pap_rejectauth: I cannot establish a connection -  it's rejected by the
other side. In the log file I find a message that's something like:
&dquot;sent (0) (LCP ConfRej id=0x1 auth pap&dquot;
<label id="pap_rejectauth">
<p>
Your computer is refusing to identify itself with user name (e.g. XXX) 
and password (e.g. YYY). That only works with the authorization options
&dquot;user XXX&dquot; and &dquot;remotename YYY&dquot; together with a correct (!)
/etc/ppp/pap-secrets. With a password of ZZZ it should ideally look
like this:
<code>
XXX YYY ZZZ *
</code>
If that doesn't work, you can use wild cards, something like:
<code>
* * ZZZ *
</code>
Then <em>every</em> partner has the password ZZZ. If chap is required
for authorization, then /etc/ppp/chap-secrets must be set up correctly.
Important : the format is different from that of pap-secrets!
Make sure to consult the README's, or check out:
<tt><url url="http://www.lrz-muenchen.de/&tilde;ui161ab/www/isdn/"></tt>
Also have a look at the next question: <ref id="pap_passwd">.

<sect1> pap_passwd: I have problems with PAP or CHAP authentication. It does not
work although I'm sure I entered passwords etc. correctly.
<label id="pap_passwd">
<p>
Stefan A. Muehlenweg <tt><htmlurl url="mailto:Stefan.A.Muehlenweg@samhh.Hanse.DE"
name="Stefan.A.Muehlenweg@samhh.Hanse.DE"></tt> wrote on
4 Oct 1996:
<quote>
I had exactly the same problem/the same error message. The cause for it
was that I had three entries in chap-secrets/pap-secrets (for client,
server, secret), but not a fourth one (IP addresses). BUT: after the third
entry were some BLANKs. After removing the trailing BLANKs and/or TABs
(i)pppd is now very satisfied with my auth-files.
</quote>
A further source of problems can be the password itself. If it contains
the &dquot;&num;&dquot; character, then everything after than is understood as a
comment. Spaces or tabs can cause similar problems. Solution: put
the password in quotes!


<!-- Isdnlog
-->

<sect> Isdnlog

<sect1> isdnlog_2callerid: Isdnlog (=2.52) shows for a caller <em>two</em>
telephone numbers! Which one is correct?
<p>
The caller has most likely activated the (costly) feature CLIP
(= Calling Line Identification Presentation, no screening), which means 
any telephone number can be transmitted. See the question &dquot;I've heard
that actually two Caller IDs are transmitted?&dquot;.

Andreas Kool <tt><htmlurl url="mailto:akool@Kool.f.EUnet.de"
name="akool@Kool.f.EUnet.de"></tt> wrote on 26 Jan 1997:

In any case, you can only fool software/PBXs that do not evaluate
the screening indicator - isdnlog with version 2.52 shows both the
correct *and* the faked telephone number.

...CLIP, no screening was actually designed for transmitting internal
company numbers in the public network.


<sect1> isdnlog_soundbusy: I've set up a script to play sound per cat on
/dev/sound or some other device. When several events occur, then there is an error:
<tt>Can't open output file '/dev/sound': Device or resource busy</tt>
<p>
Only one process at a time can access the sound device. You need an upper
instance that coordinates access to the sound device. NAS (network audio
system), and rplay can be used for this.

<sect1> isdnlog_noshell: Isdnlog should call a program with redirected output
(e.g. <tt>play anruf.au 2/dev/null</tt>). Why does ISDN tell me
<tt>Can't start '/usr/local/bin/play anruf.au 2/dev/null' with execvp()</tt>?
<p>
Because isdnlog is not a (Bourne) shell ;-) Isdnlog can only start
<bf>real</bf> programs. Just write a little script for it and make it
executable (chmod +x):
<code>
&num;!/bin/sh
/usr/local/bin/play anruf.au 2/dev/null
</code>

<sect1> isdnlog_blankscreen: When dialing out, the screen goes momentarily black?
<p>
This may happen when you start isdnlog with the options <tt>-t
1</tt> or <tt>-t 2</tt>, then the time is synchronized with the digital
switching station. The screen saver thinks that more than x minutes have
passed, which causes a short blackout of the screen.


<!-- Unwanted dialouts
-->

<sect> dod: Unwanted dialout on demand
<label id="dod">

<sect1> dod_how: How does dialout on demand work?
<p>
After you habe set up a network interface, and defined a route to it, then all
ip packages will be routed to this interface. If the <tt/autodial/ mode has
been enabled (see question <ref id="config_dialmode"> on the dialmodes) then
the interface will automatically trigger a dialout when it receives ip
packages.

<sect1> dod_causes: What can cause a charge unit disaster?
<p>
There are many possibilities.
<enum>
<item>You compiled your kernel with the option Bridging by mistake
<item>ARP requests or broadcasts? You should run ifconfig with the options
<tt>-arp</tt> and <tt>-broadcast</tt> to keep from opening connections in this
way. You can recognize this one when you have a dialout, but <em/no/ data is
transferred.
<item>Other Broadcasts from the interfaces were being forwarded by ISDN
<item>If IP connections are still open with the line is disconnected and
IP addresses are dynamically assigned, then the disaster is inevitable.
Then a new connection is started to bring down the open IP connections,
which fails because the IP address is now different. The line is hung up,
but the IP connections are still open, the line is dialed again, and
so on... This can only be avoided with the RST-Revoking patch, which has found
its way into the 2.0.x kernels, but not into 2.1/2.2/2.3 (see the appropriate
question below).
</enum>

<sect1> dod_off: How can I safely turn off dialout on demand?
<p>
<enum>
<item>Set your dialmode properly (see question <ref id="config_dialmode">).
Alternatively you can use the dialmode feature (see question
<ref id="config_dialmode">.
<item>Delete the telephone number of the interface, or set an invalid one. Then you
can see from the complaints in the syslog whether a process wants to send
packets out to the world.
<item>Switch the system off.
<item>Delete your route to the ISDN device.
For example, to disable any automatic dialouts:
<code>
/sbin/route del default
/sbin/isdnctrl system off
/sbin/ifconfig ippp0 down
</code>
To get things running again:
<code>
/sbin/isdnctrl system on
/sbin/ifconfig ippp0 up 
/sbin/route add &dollar;GATE-IP dev ippp0
/sbin/route add default ippp0
</code>
The latter method has the disadvantage that dialin is then no longer 
possible.
</enum>

<sect1> dod_strategy: How can I track down unexplainable dialouts?
<p>
If you are using ipppd: get a tcpdump which can show data with the syncPPP
encapsulation (may require a patch - see question
<ref id="trouble_tcpdump">). Otherwise your only chance is to turn off one
daemon after the other and see if things have finally quieted down. named,
sendmail, and also smbd (Samba) are likely candidates to open connections (see
the following questions).

Christoph Trautwein <tt><htmlurl url="mailto:trautw@fzi.de"
name="trautw@fzi.de"></tt> added on 5 Nov 1996:
<quote>
I too was only able to find this out by killing suspicious processes.
More information on the search for these processes and how to make
them quite can be found at:
<tt><url url="http://www.fzi.de/sim/people/trautw/i4l/index.html"></tt>
</quote>
Herbert Rosmanith <tt><htmlurl url="mailto:herp@wildsau.idv.uni-linz.ac.at"
name="herp@wildsau.idv.uni-linz.ac.at"></tt> added on 24 Nov 1996:
<quote>
Try to find out which lookup triggers the connection with
&dquot;isdnctrl verbose 3&dquot;. Then a message should appear in
the kernel message queue (visible with &dquot;dmesg&dquot;) a'la:
OPEN: 141.76.60.54 - 193.171.67.253 TCP, port: 1686 - 540
In this example, our computer is trying to pick up mail on
port 540 (UUCP over TCP/IP over ISDN).
</quote>
Please note: only the triggering packet will be logged.

Stefan Luethje <tt><htmlurl url="mailto:luethje@sl-gw.lake.de"
name="luethje@sl-gw.lake.de"></tt> wrote further on 27 Nov 1996:
<quote>
Another tip. There are a lot of daemons on the Linux side that
broadcasts on all interfaces. This leads to frequent autodials. 
In this case you can redirected the broadcast address to the
dummy0 interface. It's not clean, but it works.
</quote>
See all the last question in this section.

<sect1> Can it be that the Win95 machine on my LAN is causing automatic
dialouts?
<p>
Stefan Luethje <tt><htmlurl url="mailto:luethje@sl-gw.lake.de"
name="luethje@sl-gw.lake.de"></tt> wrote on 27 Nov 1996:
<quote>
If in Wintel the name server of your provider is given, and
Windows 3.11/95 is started, then it has to talk to the name
server (only Bill Gates knows why).
</quote>

<sect1> I have set up a local DNS name server. Why does it cause unwanted 
dialouts? How can I find the cause?
<p>
Jens Ey <tt><htmlurl url="mailto:jens@jeyhh.shnet.org"
name="jens@jeyhh.shnet.org"></tt> wrote on 29 Nov 1996:

Turn on debug level 1 in named and look at the logfile
in /var/tmp.

In my case, I found regular DNS requests from Windows machines. The
problem was that names like WORKGROUP.domain.de were requested,
i.e. names that the DNS could not know. I'm assuming that the Windows
machine was looking for its master browser or a domain controller.

This was causing me so many problems for my Internet connection with
Linux in a LAN that I installed an external terminal adapter, set up
a proxy server, and set up diald that only DNS requests from the Linux
machine were allowed to be carried out. Then the connections are 
established only when they are actually needed. The (caching) local DNS
is only used after the connection has been established. 

<sect1> dod_win95: How can I turn off the DNS requests for WORKGROUP.xxx from my
Win95 machine?
<p>
Eike Stepper <tt><htmlurl url="mailto:isdn@esc-net.de"
name="isdn@esc-net.de"></tt> wrote on 30 Nov 1996:
<quote>
Why not simply set the &dquot;Use DNS for Windows Names Resolution&dquot;   
(or similar) to No? Then it should be quiet, at least it
is for me.
</quote>

<sect1> dod_sendmail: How can I get sendmail to not initiate any connections
without local mail being left undelivered?
<p>
First you have to get sendmail to no long open any DNS connections.
You need to activate the following features: &dquot;nodns&dquot;, &dquot;nocanonify&dquot;.

If you have a smarthost, you need to make sure that this name does not
call the name server. You can either set it directly as an IP address,
or add the name to /etc/hosts (/etc/host.conf should then contain
&dquot;order hosts bind&dquot;)

You should set all non-local mailers as &dquot;expensive&dquot;
(&dquot;define(SMTP_MAILER_FLAGS, e)&dquot;), and then forbid sendmail with
&dquot;define(`confCON_EXPENSIVE', `True')&dquot; from automatically connection
to expensive mailers. The call to sendmail should no longer include
a time for the &dquot;-q&dquot; option (e.g. only &dquot;-bd -os -q&dquot;). &dquot;-os&dquot; means that
all mail will be queued (which won't prevent local mail from being
delivered immediately). The only catch is that when booting, mail that
might still be in the queue will be sent by sendmail, even though the
network is not yet up. Therefore, when booting you should remove 
all mail from /var/mqueue before starting sendmail, and then return it 
once sendmail has been started.

Mail to expensive mailers will now only be send with the explicit
call &dquot;sendmail -q&dquot;.

<sect1> dod_samba: The samba package always triggers dialouts for me. How can I
prevent this?
<p>
Andreas Glahn <tt><htmlurl url="mailto:andreas@tao.westfalen.de"
name="andreas@tao.westfalen.de"></tt> wrote on 31 Jan 1997:
I had this problems too. Then when starting the samba daemon I gave
it the internal IP address I use here at home. Since then a samba
request is no longer sent to default, but stays here.

Take a look at the configuration with netstat and tcpdump. With tcpdump
you can quickly find out to which IP address samba is trying to
connect.

My internal Linux computer has, e.g.: 192.168.99.99

My Win95 computer:        n           192.168.99.88

On the Linux computer I started samba with:
<code>
nmdb -S -B 192.168.99.255 -I 192.168.99.99
</code>
See also the above question:  se -broadcast and possibly -arp 
when defining the interfaces!

<sect1> dod_netscape: How can I get Netscape to quit initiating dialouts when
starting?
<p>
Most likely in the preferences a non-local home page has been listed.
Only a home page that Netscape is able to load immediately (e.g.
&dquot;file://localhost/xxx&dquot;) won't cause an immediate dialout. Alternatively
you can also set up a cache daemon that saves pages that are often needed.

A proxy should not cause a dial out, even when the complete name is 
entered. Only when a new proxy is given does Netscape do a DNS
lookup (and in this special case cause a dialout.
However, on 17 Mar 97 Steffan Henke <tt><htmlurl url="mailto:henker@Informatik.Uni-Bremen.DE"
name="henker@Informatik.Uni-Bremen.DE"></tt>
wrote:
<quote>
Unfortunately reality has caught up with us. I've heard that
Netscape now in version.4.02 really does establish a
connection...
</quote>

<sect1> dod_closeipconnect: After closing the line, I discover with <tt>netstat
-nt</tt> that IP connections are still open. How can I close these manually?
<p>
You can bring the interface &dquot;down&dquot; then back &dquot;up&dquot;. When
you do this, it will try to dial out. But if you have removed the outgoing
telephone number, then &dquot;no outgoing number...&dquot; appears in the
syslog, and as soon as the interface is &dquot;up&dquot;, all connections will
be closed.

<sect1> dod_openlineoncrash: Is it possible that even with a crashed computer a
ISDN connection remains open (and the charge units accumulate)?
<p>
Karsten Keil <tt><htmlurl url="mailto:keil@temic-ech.spacenet.de"
name="keil@temic-ech.spacenet.de"></tt> wrote on 11 Feb 1997:
I'm guessing, that with the status enquiry (in Switzerland - Ed.) you
simply want to make sure that when the user side has crashed, the connection
is broken. This is in addition to the Layer 2 monitoring and is not
totally senseless, since with many cards/end devices the ISAC is run in 
auto mode and therefore a crash would keep the connection open.

However, i4l runs the ISAC in nonauto mode, meaning that when interrupts
are no longer being process, the connection is broken after a maximum
of about 1/2 a minute. This is not the reason for using nonauto mode, but
this is a safety feature ;-), but doesn't mean that the charge unit 
disaster is impossible.


<!-- Dialin Server
-->

<sect> Dialin

<sect1> dialin_ignored: I keep getting the message &dquot;isdn_tty: call from
XXX - YYY ignored&dquot;. Why does isdn4linux (syncPPP) ignore this dialin
attempt?
<p>
There are two possible explanations. Either your own MSN (here: YYY)
is not correctly set with &dquot;isdnctrl eaz interface YYY&dquot;. Or 
&dquot;isdnctrl secure interface on&dquot; was set, without allowing calls from
the incoming number (here: XXX) with &dquot;isdnctrl addphone interface in XXX&dquot;.

<sect1> dialin_async: A SunISDN tries to dial into my i4l system.
<p>
The Sun tries to communicate with asyncPPP. ipppd can't handle
this, you have to use the ttyI* devices and the standard pppd.



<!-- Callback
-->

<sect> Callback

<sect1> callback_delay: An incoming call is rejected by i4l. i4l then calls
back. The reject is not recognized by the other side which keeps on dialing to
i4l.
<p>
Most problems with callback can be solved by adjusting the callback
delay with &dquot;isdnctrl cbdelay&dquot;. One second has been successful in
many cases.

<sect1> callback_cisco: Somehow i4l can not callback a Cisco?
<p>
Torsten Hentschel <tt><htmlurl url="mailto:Torsten.Hentschel@DInet.de"
name="Torsten.Hentschel@DInet.de"></tt> wrote on 3 Oct 1996:
<quote>
A Cisco may dial so heavily that the ipppd has no chance to callback.
That's how they are programmed (firm statement of a Cisco developer):
If a Cisco receives a packet that should be routed through a &dquot;dial on
demand&dquot; telephone connection, and there is a D-channel available for
dialing out, it dials out immediately.
If in such a situation (which has be the case with Delta Internet for half
a year now) a Cisco with 8 D-channels is on the other side and somebody
does a simple &dquot;ping RemoteIP&dquot; then the Cisco will use (worst case) all
8 D-channels to dial out. Of course it can't dial the same telephone
number with two D-channels in parallel (would be immediately busy). Its
programming is not so stupid, but it sets up the next D-channel for
dialout before it assumes the previous D-channel as failed. Such a Cisco
works like a machine gun in respect to dialout. And i4l won't get a free
D-channel for dialin if the Cisco doesn't want.
The bad thing: a Cisco always expects (even when configured on &dquot;callback
client&dquot; = i4l dials back) that the other side unhooks the line, then both
hang up and then comes the callback. Username and password always have to
be exchanged before the callback is allowed when using PPP, to be sure
that the person requesting callback is allowed to do so. (Cisco seems to
obey the rules of the (German) Telekom that no information are to be ex-
changed without a B-channel connection. A callback request just by caller
id could in doubt be considered as a transmission of information).
</quote>
Torsten Hentschel <tt><htmlurl url="mailto:Torsten.Hentschel@DInet.de"
name="Torsten.Hentschel@DInet.de"></tt> additionally wrote on
20. Nov 1996:
<quote>
I've often tried callback over PPP with two CISCOs. From my experience,
trials in the combination CISCO - Linux will not be successful.
A CISCO always handshakes a callback request via PPP. To do this, the
other side has to first unhook and then do all the handshaking
(authentication,...). Then both hang up and the callback is placed.
isdnctrl commands of Linux influence only the kernels net devices
and have no or hardly any influence on how the ipppd handles callbacks.
He does not recognize that he is supposed to expect that the remote
side calls back.
Accordingly he rejects the offer of the CISCO via PPP, that the CISCO
is ready to call back. Then the CISCO assumes that it should not call
back (it wants to see an explicit callback request during the PPP
handshaking).
The CISCO will confirm this when you log onto it and check with these
commands:
deb ppp chap
deb ppp negotiotion
deb ppp error
term mon
its debug messages about the dial in trials of your Linux computer.
You have to do this via telnet instead of on the console - otherwise
the CISCO won't be able to handle the logging via the serial interface.
</quote>

<sect1> callback_ascend: Callback from an Ascend works only when I set
&dquot;Active=Yes&dquot; in the Ascend menu; but then the Ascend keeps calling
me, even when my machine is off.
<p>
Ulrich Klein <tt><htmlurl url="mailto:ulik@hprc.tandem.com"
name="ulik@hprc.tandem.com"></tt> wrote on 14 Dec 1996:

Somewhere in the Ascend menus you can set &dquot;dial broadcast&dquot; to &dquot;no&dquot;
or &dquot;off&dquot;. Otherwise the thing will dial with every broadcast. At
least that helped me. In case anyone from the network on which the
Ascend is attached really wants to establish a connection, then you
have to use the strange filters. I believe there's one that will
dial out only for callback.

<sect1> callback_banzai: How can I callback a Banzai!? 
<p>
Jan-Olaf Droese <tt><htmlurl url="mailto:jano@layla.RoBIN.de"
name="jano@layla.RoBIN.de"></tt> wrote on 31 Jan 1997:

On the Banzai side, a  `c' should be added to the outgoing number,
so it will be ready for the return call. Just to be safe, you can
the dialout attempts on the Banzai to 1, so there won't be any
call collisions.
On the i4l I've set the following:
<code>
isdnctrl callback isdn0 in
isdnctrl cbdelay isdn0 1
</code>


<sect> Supported Countries
<label id="countries">
<!-- Countries and further features
-->

<sect1> country_which: In which countries does isdn4linux work?
<p>
We are aware of at least the following countries:
<itemize>
<item>Austria
<item>Australia
<item>Belgium
<item>Denmark
<item>Finland
<item>France
<item>Germany
<item>Ireland
<item>Israel
<item>Italy
<item>Norway
<item>Peru
<item>Portugal
<item>Singapore
<item>Spain
<item>Sweden
<item>Switzerland
<item>The Netherlands
<item>United Kingdom
<item>USA
</itemize>
If your country is not on this list does not mean it is not supported. It just
means we have not seen a confirmation about its usage there. Check the mailing
list for other users from your country.

<sect1> country_certified: Is isdn4linux approved for use by the
telecommunications authorities?
<label id="country_certified">
<p>
<descrip>
<tag/Germany/
That depends on the driver used. For active cards, the approval 
covers the entire card including its firmware. Thus the approval 
also covers the use of these cards with isdn4linux. The Elsa Quickstep 1000 PCI
driver is currently certified in Germany (and hence in most european
countries). This applies to the 2.0.36 kernel version.
<tag/Other countries/
Besides those countries that accept a german certification,
we don't have any information... does anyone know more?
</descrip>

<sect> 1tr6: German Pecularities (1TR6)

<sect1> 1tr6_eaz: Which EAZ should I use for i4l?
<p>
You can use all available EAZ. However, two EAZ have a special meaning and
can cause problems:
<verb>
EAZ 0: global call (all telephones ring)
EAZ 9: global call (no telephone rings)
</verb>
Gernot Zander <tt><htmlurl url="mailto:hifi@scorpio.in-berlin.de"
name="hifi@scorpio.in-berlin.de"></tt> wrote about this on 6. Jan 1997:
<quote>
I would not use 0, for my taste it is too likely that i4l will steal
all voice connections.
</quote>

<sect1> 1tr6:extension: I use 1TR6 on an extension - the extension number has
more than one digit (e.g. 206). What is my EAZ?
<p>
Jens Ey <tt><htmlurl url="mailto:jens@jeyhh.shnet.org"
name="jens@jeyhh.shnet.org"></tt> wrote on 10 Jan 1997:

The EAZ for extensions is usually the last digit of the extension number.
As EAZ for the Linux computer you should then enter a '6'.

<sect1> 1tr6_spv: What is a SPV?
<p>
SPV stands for &dquot;semipermanente Verbindung&dquot; (semipermanent connection)
and is a (soon to be obsolete) specialty of the German Telekom. Like
a leased line, the calling partner is fixed, however the connection
is only established as needed (which occurs very quickly, much quicker
that a dial connection). Since the Telekom can use the line for other 
things when it's not needed, the SPV is cheaper than a leased line.

This SPV is not to be confused with the Austrian understanding of SPV. The
Austrian `SPV' has one channel leased line, and one channel for dialing.

<sect1> 1tr6_spvavailavle: How long will there still be SPVs?
<p>
Steffen Sledz <tt><htmlurl url="mailto:sledz@dgroup.de"
name="sledz@dgroup.de"></tt> wrote on 5 Dec 1996:
<quote>
Due to a couple of lawsuits against the Telekom before the 
European Court of Justice, most likely until the end of
1997. This will be posted in the appropriate newsgroups
and probably also at
</quote>
<tt><url url="http://www.birch.de"></tt> (who is suing).

<sect1> 1tr6_spv: Does isdn4linux support SPVs? How?
<p>
To switch on the support for SPVs, add an &dquot;S&dquot; before the number
to be dialed. This works (quite well) for modem emulations as well
as for defined network interfaces.


<sect> Other countries


<sect1> country_austria: Austria: We have neither an MSN nor an EAZ, only a
normal plain telephone number. What do we have to use for i4l?
<p>
In Austria ISDN lines are by standard installed <em>without</em> MSN (which is
different from Germany). That means when somebody calls the installed ISDN
number the called party gets signalled a &dquot;global call&dquot;. i4l then says
&dquot;incoming call without CPN&dquot; - &dquot;CPN&dquot; means called party number.
Solution: Set the incoming &dquot;MSN&dquot; (in reality: none) to &dquot;0&dquot;, then i4l
responds to the global call. Otherwise it waits for the signalling of the
number you told i4l, and that won't happen (happens only for *additional*
MSN). The same applies to the setup of your getty.

On the other hand you should set the outgoing MSN correctly (without area
code) -- however, a wrong MSN will be replaced with the correct one by your
telecommunications provider.

<sect1> country_france: France: How does our MSN look like?
<p>
If you don't have MSN, you need to specify as local number only the last 4
digits of you phone number. A good thing is that you can also use
sub-addressing. If your phone number is 01 41 33 67 87, and you want to use
sub-address 02, then configure the local phone number of the HiSax driver as
6787.02 .

<sect1> countr_italy: Italy: What does our MSN look like?
<p>
isdn4linux also works in Italy (ICN card). The MSN must be the phone number
with the Italian area code  but without the leading 0. For example, if my phone
number is 72004681 and my area code is 045, my MSN is 4572004681.
Now with the setting AT&amp;E4572004681 isdn4linux works fine.

<sect1> country_netherland: Netherlands: What does our MSN look like?
<p>
In The Netherlands the MSN includes (as opposed to the German 
Telekom) <em>also the area code</em> - but without the leading zero. 

<sect1> country_northamerica: North America: Can we use isdn4linux in North
America?
<p>
Unfortunately, European ISDN cards can not be used in North America.
In Europe, the telephone company normally makes the network terminator
(NTBA) available. In North America <em>the customer</em> has to supply such
a device(NT-1) himself! Therefore, most ISDN cards offer an 
integrated NT-1.

There are also other differences; e.g. in Europe a PRI (Primary
Rate Interface) has 30 B channels, in North America only 23. Also the
C channel protocol NI-1 is used. NI-1 is related to DSS1 (both are Q.931
Protocols), but both have totally different groups of functions and are
therefore not compatible to one other.    

However, the firm &dquot;Spellcaster&dquot; has written an isdn4linux driver
for its own (active) cards. More information is available from:
<verb>
Ian James
Customer Service Manager
SpellCaster Telecommunications Inc.
73 Laird Drive, Suite 206
Toronto, Ontario
Canada M4G 3T4
Phone: 1 (800) 238-0547
Fax: (416) 425-0854
</verb>
E-mail:  <tt><htmlurl url="mailto:ipj@spellcast.com"
name="ipj@spellcast.com"></tt> or <tt><htmlurl url="mailto:sales@spellcast.com"
name="sales@spellcast.com"></tt>
<tt><url url="http://www.spellcast.com"></tt>

<sect1> country_portugal: Portugal: What should we use as MSN?
<p>
As long as only one telephone number or MSN was applied for, the telephone
company sends no caller ID. Therefore the MSN should be set to &dquot;0&dquot;.
If more than one MSNs was applied for, then these should be set as usual.

<sect1> country_switherland: Switzerland: We have neither an MSN nor an EAZ, just a plain telephone
number. What do we have to use for i4l?
<p>
In Switzerland you have to use the <em>last digit</em> of your telephone
number as your MSN/EAZ (&dquot;6&dquot; if you have the telephone number &dquot;123456&dquot;).

<sect1> country_uk: UK: What should we use as MSN?
<p>
There are no normal MSNs in UK. Each MSN is actually a single digit, 0 - 9,
corresponding to the last digit of the actual phone number. Apparently in the
UK you either have *no* MSNs, or 10 MSNs; you then always get a block of 10
sequential numbers. It was said that BT was going to offer &dquot;normal&dquot;
EuroISDN, which they wanted to call ISDN-2e (their current offering is
ISDN-2). However, so far I have not received any feedback on this.


<sect> misc: Miscellaneous

<sect1> misc_ntbadipWhere can I find information on the dip switches of my NTBA?
<p>
<tt><url url="ftp://novix.oih.rwth-aachen.de/pub/ntba.zip"></tt> (ca. 170kB)

<sect1> misc_nonullcable: Can I connect two ISDN devices directly with a kind
of &dquot;null modem cable&dquot;?
<p>
No, that's not possible. The concept of ISDN doesn't allow it. A NTBA or a
PBX with an internal bus is required.

<sect1> misc_uisdn: Can isdn4linux run in parallel to UISDN?
<p>
Yes. Both ISDN packages load the module isdn.o, otherwise the naming conventions
are different. Tip: rename Urlichs isdn.o to uisdn.o, and change
lib/modules/modules.isdn (or whatever the file is called that lists the modules
and is read by the script) accordingly. Happily the default names of the ISDN
devices are also different.



<!-- Glossary
-->

<sect> Glossary
<p>
<descrip>
<tag/AOC-D/
&dquot;Advice Of Charge During the Call&dquot;.

<tag/AOC-E/
&dquot;Advice of Charge at the End of the Call&dquot;. In Germany, this
service	is included in the &dquot;Komfort&dquot; connection.

<tag/CLIR/
CLIR (Calling Line Identification Restriction) can be offered by
the ISDN provider: one can (from call to call) restrict the
identification of one's own caller ID to the other party. In Germany,
this must be applied for but is without charge (however call by call
transmission of the caller ID costs extra).

<tag/COLP/
COLP (Connected Line Identification Presentation) can also be offered
by the ISDN provider. If you've applied for COLP, you get an extended
dialing protocol. You will receive feedback from your telecommunication
company who picked up your outgoing call.
In Germany, it must be applied for, and costs extra. More information
than COLP can be obtained with the help of a reverse-connected ISDN
card.

<tag/CVS Tree/
The i4l developers have formed a team. The tool CVS allows the
members to easily make patches. The history of the project is also
thereby documented, and it is also not difficult to reproduce older
versions.

<tag/HDLC/
A widely used low-level protocol.

<tag/HSCX/
A Siemens chip which is, similar to ISAC, on many passive cards.
It takes over the serial bus from ISAC and demultiplexes when 
receiving or multiplexes (i.e. inserts the bits in the correct
position) the B channels.

<tag/ISAC/
A Siemens chip which is, similar to HSCX, on many passive cards.
It is responsible for Level 1, so it sits (almost) directly on
the line. It handles the D channel protocol and sends the
S0 data to a special serial bus (IOM). When sending it does the
opposite.

<tag/TEI/
TEI stands for Terminal End Identifier. The local switching station, or
with an internal S0 the PBX, automatically or permanently assigns each
end device a TEI. This simply allows the addressing of the D
channels. TEIs have the following values:
0- 63   permanent TEIs (e.g. 0 is used for point to point connections)
64-126   automatically assigned
127   broadcast to all devices (e.g. an incoming call)

<tag/PBX/
A PBX (Private Branch eXchange) is used to connect different internal
devices to the ISDN network. This is usually for analog devices that
cannot be directly connected to an ISDN network. The PBX can also make
an internal digital S0 bus available, on which ISDN devices can be
connected. This allows for local calls without using the switching
station (thereby avoiding the charges from your telephone company).

<tag/MSN/
Unlike a normal telephone connection, an ISDN connection can have more
than one telephone number - each of these is called an MSN (Multiple
Subscriber Number).

<tag/EAZ/
This is a German name for an MSN. In Germany, EAZ and MSN are used
as synonyms, though in theory one ought to differentiate according
to the protocol used. That which is called MSN in the Euro-ISDN
protocol was called EAZ in the German 1TR6-ISDN protocol (a German
predecessor to Euro-ISDN).
</descrip>


</article>


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