Hi Humza,
I've checked the traces and from what I can see is that T.38 negotiation is never finished end to end.
What I can see is that from telco after sending an invite we get:
v=0
o=BroadWorks 427038729 1 IN IP4 172.30.152.132
s=-
c=IN IP4 172.30.152.132
t=0 0
a=sqn: 0
a=cdsc: 1 image udptl t38
a=cpar: a=T38FaxVersion:0
a=cpar: a=T38FaxUdpEC:t38UDPRedundancy
m=audio 10154 RTP/AVP 8 101
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
But then CUBE is sending over to on call leg to CUCM:
v=0
o=CiscoSystemsSIP-GW-UserAgent 6334 9992 IN IP4 10.60.7.11
s=SIP Call
c=IN IP4 10.60.7.11
t=0 0
m=audio 30994 RTP/AVP 8 101
c=IN IP4 10.60.7.11
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
So T.38 capabilities are not there. So CUBE is stripping those capabilities. But I think it's doing it as per design, cause according to all Cisco standards it would expect to first negotiate normal call, and then after initial call is setup then switch over.
As mentioned on the slide below:
So after call is establish I'd expect telco site to send over RE-INVITE with T.38 capabilities once again, which never happens. And as the end result SIP Telco thinks they are doing T.38 and between GW and FAX server we have just normal call negotiated.
Is there any chance to contact telco to see if they can hold FAX negotiation till after call is established.
Maybe there is also some command on CUBE to make it resend this T.38 capabilities toward CUBE after initial negotiation is done, but I don't know any.
Leszek
