Broken call with Warning-Message


I have an * with this configuration:
Asterisk 1.2.17
Zaptel 1.2.16
Libpri 1.2.3
running on Ubuntu…

Sometimes I got the following Warning on the CLI:

WARNING[4262]: chan_sip.c:7104 check_via: Don't know how to respond via 'SIP/2.0/TCP'

and the call is going down.
The call comes first from PSTN (german-PRI) into another *-machine (with TDM400-card).
This machine is connected vi IAX2-Trunk to the * where the Warning appears.

Here is the part in extensions.conf

exten => 160704,1,Answer()
exten => 160704,2,SetCallerID(abc)
exten => 160704,3,Queue(abc,r,,,180)
exten => 160704,4,Set(CT=${STRFTIME(${EPOCH},GMT+1,%d-%m.%C%y-%H_%M_%S)})
exten => 160704,5,Wait(2)
exten => 160704,6,Playback(message)
exten => 160704,7,Record(/var/spool/asterisk/record/M-${CT}.gsm,3,120,x)
exten => 160704,8,Hangup()

I think the call get broken right after a SIP-client, wich is logged-in in queue ‘abc’, has taken the call.

Any ideas?!


Seems the sip client uses the tcp protocol as transport for the sip signaling, Asterisk, if I’m not wrong, uses only the udp protocol as transport, so try force the client using only udp as transport.