[cisco-voip] Fax !!! at my wits end!!!

[Ryan Huff]

Based on this (regarding the MTP), and the previous SDP audio header; it’s very clear something is changing the DTMF method (which is why MTP is “fixing” it). Non negotiable DTMF can absolutely cause a call to fail, especially faxing (because the other side effectively won’t “hear” the handshake).

In your “bad call” SDP, there was no DTMF method listed, whereas your “good call” SDP listed 101 (rtp-nte). In both cases, the codec remained the same (PCMU/8000)

I would get a SIP message log from every joint in the call leg and look for where DTMF is changing and verify every piece in the call leg (and associated node’s/HA’s of said pieces) all support and agree to the same DTMF method (also verify you’re supporting at least one OOB DTMF method).

On Mar 23, 2018, at 12:36, Jonatan Quezada <jonatan.quezada at chemeketa.edu<mailto:jonatan.quezada at chemeketa.edu>> wrote:

is anyone using the century Link configuration guide for the SIP IQ private on a 4431, . I finally have calls 100 percent of the time but I had to do MTP on the trunk for the CUCM

my call flow is very simple

centLiunk---IQ private---- Cube---------CUCM,uccx,Unity,

trying like mad for fax pass through,

I have tried multiple combinationsof these:

voice class codec 1  ---this one is pretty static, I havent changed it
 codec preference 1 g711ulaw
 codec preference 2 g729r8

sip profile
request ANY sdp-header Audio-Attribute modify "a=X-cisco-media:umoh" ""
!
voice service voip
 no supplementary-service sip moved-temporarily
 redirect ip2ip
 fax protocol pass-through g711ulaw

sip
  midcall-signaling passthru media-change
  early-offer forced
  privacy-policy passthru
  pass-thru subscribe-notify-events all
  pass-thru content unsupp
  pass-thru content sdp


I thinking about picking apart my config all together and going strictly off of config example. I had our vendor engineer do ours and its been nothing but head aches. a couple of the huge differences are the DPG references and huge header modification, What do you guys suggest?



Johnny Q
Voice Technology Analyst - TelNet
Chemeketa Community College
Johnny.Q at chemeketa.edu<mailto:Johnny.Q at chemeketa.edu>
Building 22 Room 131
Work 5033995294
Mobile 9712182110
SIP 5035406686
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