asterisk users - Jun 2004 - Call Transfer over Fritz!-ISDN Card with i4l does not work

Hello everybody!

After checking the complete wiki and the mailinglist archives I still
haven't really found out why the following constellation does not work.

We have an asterisk-System with some SIP-Phones and an old ISA
Fritz-ISDN-Card used with i4l. The whole system is integrated in out
(ISDN-)PBX for testing.

The ISDN-Card is properly configured, as we are able to phone out,
receive calls, etc. The only thing that is not possible, is to transfer
a call received on one ISDN-channel to the other (unused) ISDN-channel.
Whenever I try that, all connections are disconnected. Forwarding an
incoming ISDN-call to a SIP-Phone works fine.
How can this behavior be explained. Should I use an ISDN-CAPI driver to
realise the call transfers, or do I need a newer Card?

I would appreciate any information that will help me solve this problem.

Best regards

Kai

-- 
Kai Militzer                 WESTEND GmbH  |  Internet-Business-Provider
Technik                      CISCO Systems Partner - Authorized Reseller
                             L?tticher Stra?e 10      Tel 0241/701333-11
km@westend.com               D-52064 Aachen              Fax 0241/911879