[Asterisk-Users] SIP => Zaptel TDM400P issue

[Dustin Mulcahey]

Situation:
SIP phone A calls Asterisk.
Asterisk forwards to another SIP agent B.
The SIP agent B forwards A back to an Asterisk extension that is mapped
to a TDM400P channel

Once all of this has transpired, there is no audio channel between the
SIP phone A and the TDM400P.

If A is not registered with Asterisk performs the same sequence, a half-
duplex connection results in which A can hear the TDM400P, but not the
other way around.

If the above procedure is repeated in reverse, that is:
TDM400P dials the extension of SIP agent B.
SIP agent B forwards TDM400P to the asterisk extension of SIP A.

A full duplex connection results, and everything is normal.

Any ideas?  Elaborations needed?

===sip.conf===============
[general]
port = 5060			; Port to bind to
bindaddr = 192.168.0.104		; Address to bind to
context = from-sip-internal
disallow=all		
allow=ulaw

[201]
username=201
type=friend
secret=password
host=dynamic
dtmfmode=inband
===============================

201 is SIP phone A.

-Dustin Mulcahey