SIP Trunk FAX T.38 /G711 two m-line

[ROLAND MARTI]

Hi All

mybe there is an old problem. We have to replace our ISDN FAX connection with SIP Trunk.

Design:

FAX Server(Kofax) - CUBE(CS-4451 IOS XE Software, Version 16.03.05) - TelkoProvider(Sunrise)

Prefered Codec for FAX : G711 aLaw

Now we have a problem that after the first connect with G711 aLaw the Provider send us an REINVITE with two m-lines. First T38 / second G711.

The CUBE dosn't handle this correct and send an 488 Not Acceptable Media CSCue70469

My question is it possible to change the order of the m-lines with sip-profiles.

m=image 21228 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:9600
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:200
a=T38FaxUdpEC:t38UDPRedundancy
m=audio 21230 RTP/AVP 8 0 121
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:121 CLEARMODE/8000
a=ptime:20
a=fax

Thank you 

Roland

[kevin.vines]

I found this tech note but the sip-profile never seems to get invoked. Not sure what I'm doing wrong...

https://www.cisco.com/c/en/us/support/docs/unified-communications/unified-border-element/118939-technote-cube-00.html

[R0g22]

Can you give more details about what you are trying to do and what is not working ?

[Daniele Giordano]

Try this configuration:

voice service voip

sip

pass-thru content sdp

In this way the SDP is not negotiated by CUBE but passed directly to your fax:

"Passes the SDP transparently from in-leg to the out-leg with no media negotiation."