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Audio Clipping with SIP Trunk and UCCX

jecker
Level 1
Level 1

Hello,

I am running CUCM 11 and UCCX 11 with a SIP trunk for PSTN connectivity.  I have several UCCX queues that work great internally but as soon as I make a call inbound from the SIP trunk I get audio clipping after a Call Unhold event. 

Here is the basic UCCX script:

 - call in queue

 - call hold

 - delay 30 seconds

 - call unhold

 - Play prompt ( the first 2 seconds of the prompt is clipped off and is just silence)

Here is the call flow:

ITSP>--SIP-->CUBE>--SIP-->CUCM>--JTAPI-->UCCX

Here is part of my cube config:

voice service voip
 ip address trusted list
  ipv4 10.150.21.5
  ipv4 10.150.20.5
  ipv4 71.161.127.11
  ipv4 71.161.127.26
 address-hiding
 mode border-element
 allow-connections h323 to h323
 allow-connections h323 to sip
 allow-connections sip to h323
 allow-connections sip to sip
 supplementary-service h450.12
 fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback none
 h323
 sip
  rel1xx disable
  midcall-signaling passthru media-change (I've tried this with media-change and without)
  early-offer forced

Any ideas?

4 Replies 4

Deepak Mehta
VIP Alumni
VIP Alumni

I have seen these clipping issues when we call outbound to a PSTN and SIP trunk is not set to send PRACK for 1XX messages.

So you need to make sure SIP trunk is set to send PRACK for all 1XX messages received from service provider.

In the SIP trunk early offer support for voice and video calls should be enabled as well.

Thanks for the info.  I tried to enable PRACK for 1XX messages but it didn't seem to make a difference. 

Hello there, I am facing the same issue with the same scenario. May I ask if you were ever able to find the source of the issue?

I opened a TAC case but the engineer was not able to fix the issue and I needed to get the issue resolved.  Unfortunately I just added a couple seconds of padding to each message played in UCCX and all worked fine. 

I wish I had found the root problem for the issue instead of putting a work around in place, but I needed to get the call center up and running.   

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