Since version 5.8.0 the perl interpreter may expect all filehandles to

be in UTF-8 depending on the locale settings.  isdnlog and its tools are
completely unaware of unicode, so the default encoding is set back to
iso-8859-1 (latin1).  The backward compatible notation was hinted by
Leopold Toetsch.  The changes for perl 5.8.0 are described at
http://www.perldoc.com/perl5.8.0/pod/perldelta.html#PerlIO-is-Now-The-Default

isdnlog/tools/dest/CDB_File_Dump.pm

@@ -59,6 +59,8 @@ use vars qw(@ISA);
 require Tie::Hash;
 
 BEGIN {
+    # perl 5.8.0 could use UTF-8 as default encoding, which has to be prevented.
+    eval q( use open ':encoding(iso-8859-1)' );
     @ISA=qw(Tie::StdHash);
 }
 

isdnlog/tools/dest/makedest

@@ -25,6 +25,8 @@
 
 
 package main;
+# perl 5.8.0 could use UTF-8 as default encoding, which has to be prevented.
+eval q( use open ':encoding(iso-8859-1)' );
 use wld;
 BEGIN {
   if ( (! exists $ENV{DBEXT} or $ENV{DBEXT} eq ".cdb") and

isdnlog/tools/dest/pp_rate

@@ -11,6 +11,8 @@ use wld;
 use strict;
 use IO::File;
 $|=1;
+# perl 5.8.0 could use UTF-8 as default encoding, which has to be prevented.
+eval q( use open ':encoding(iso-8859-1)' );
 use vars qw( %names $COUNTRY %myalias $co_dat );
 use vars qw( $rtags_filename @rtags );
 $COUNTRY = '../country';