09-25-2009 05:41 AM - edited 03-17-2019 09:50 PM
Hi all,
I'm having the folowing problem regarding sip t38 with the folowing scnario:
FAX-FXS-2801-GW---->SIPv2-TRUNK---->CM7.1.2----->CUBE------>SIP-TRUNK-PROVIDER
When i try to send a fax to the sip trunk the cube send a invite with t38 in the sdp to the callmanager but the the callmanager adds a second mline with g711a that prevents the gateway to switch to t.38.
No. Time Source Destination Protocol Info
33 19:58:38.705933 10.210.40.240 10.200.0.68 SIP/SDP Status: 200 OK, with session description
Frame 33 (1046 bytes on wire, 1046 bytes captured)
Ethernet II, Src: Cisco_bb:5a:80 (00:25:45:bb:5a:80), Dst: HewlettP_62:83:3e (00:23:7d:62:83:3e)
Internet Protocol, Src: 10.210.40.240 (10.210.40.240), Dst: 10.200.0.68 (10.200.0.68)
User Datagram Protocol, Src Port: sip (5060), Dst Port: sip (5060)
Session Initiation Protocol
Status-Line: SIP/2.0 200 OK
Message Header
Message Body
Session Description Protocol
Session Description Protocol Version (v): 0
Owner/Creator, Session Id (o): CiscoSystemsSIP-GW-UserAgent 7851 2943 IN IP4 10.210.40.240
Session Name (s): SIP Call
Connection Information (c): IN IP4 10.210.40.240
Time Description, active time (t): 0 0
Media Description, name and address (m): audio 0 RTP/AVP 8
Connection Information (c): IN IP4 10.210.40.240
Media Attribute (a): rtpmap:8 PCMA/8000
Media Description, name and address (m): image 18648 udptl t38
Connection Information (c): IN IP4 10.210.40.240
If i put the the folowing scenario:
FAX-FXS-2801-GW---->SIPv2----->CUBE------>SIP-TRUNK-PROVIDER
The fax send with t.38 with no problem, the only diference is on the invite with t.38 that does not have the first mline for g711a
Frame 33 (1046 bytes on wire, 1046 bytes captured)
Ethernet II, Src: Cisco_bb:5a:80 (00:25:45:bb:5a:80), Dst: HewlettP_62:83:3e (00:23:7d:62:83:3e)
Internet Protocol, Src: 10.210.40.240 (10.210.40.240), Dst: 10.200.0.68 (10.200.0.68)
User Datagram Protocol, Src Port: sip (5060), Dst Port: sip (5060)
Session Initiation Protocol
Status-Line: SIP/2.0 200 OK
Message Header
Message Body
Session Description Protocol
Session Description Protocol Version (v): 0
Owner/Creator, Session Id (o): CiscoSystemsSIP-GW-UserAgent 7851 2943 IN IP4 10.210.40.240
Session Name (s): SIP Call
Connection Information (c): IN IP4 10.210.40.240
Media Description, name and address (m): image 18648 udptl t38
Connection Information (c): IN IP4 10.210.40.240
Can any one tell me what is the diference on the gateway on receiving the two diferent invite.
Thanks
09-25-2009 07:34 AM
It sounds like CUCM is adding this into the INVITE.
You may have an MTP involved here. If so, it needs to be on IOS, and you need to have 'codec passthrough' as one of the capabilities enabled.
I would 'debug ccsip messages' on both CUBE and the fax gateway, and see what the difference is. I haven't seen an IOS gateway add G711ulaw/alaw into a fax invite personally, so my suspicion is with CUCM.
-nick
09-25-2009 07:39 AM
Hi nick,
From the traces that i have taken i can see that the callmanager is adding the m line to the invite. I dont have any mtp involve in the call. I have to fing if is there any way to remove that m line from the invite.
Thanks
patcbr600
09-25-2009 08:01 AM
What version CUCM?
09-25-2009 08:37 AM
CM 7.1.2
09-28-2009 04:48 AM
Hi,
Just for note, i have found in sip profile that the folowing option was checked by mistake:
Outgoing T.38 INVITE include audio mline
After uncheck everithing works
Thanks
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