You need a pppd with plugin support:
	kernel 2.2.X	-	ppp-2.3.11
	kernel 2.3.99	-	ppp-2.4.0b2

usage example:

Make a single call to arcor:
	pppd call isdn/arcor

Make a call on demand to arcor:
	pppd demand connect "" idletime 30 holdoff 1 call isdn/arcor

Make a multilink call with to channels to AVM test server:
(Only working with 2.3.99-pre8 with ppp_synctty patch)
	pppd call isdn/avm-ml
	pppd call isdn/avm-ml

Make a single call to arcor with outside dialing prefix "0"
	pppd call isdn/arcor numberprefix 0

Make a single call to arcor using controller 2:
	pppd call isdn/arcor controller 2