IP Communicator one way audio with built in bridge

[Jason Bree]

I have an odd issue that started in the last couple weeks.  Agents on IP Communicator, with built in bridge enabled for call recording, get one way audio for the first 15 seconds of the call when connected to VPN.  After 15 seconds audio works. The remote agent cannot hear the other party.  Does not matter which side originates the call.   Call manage trace is showing media start event immediately upon connection.  If I disable built in bridge audio works right away.  Disabling recording on the line has no effect.  

In my mind it has to be firewall/VPN related.

Ideas?

Thanks

Jason

[joshua.gertig]

ughh... I think I saw something very similar a few years ago, but can't remember the details (and it was a different employer). Have you tried checking the box on the device level for "MTP Required"?

[luis_cordova]

Hi @jason Bre,

Check this discussion of the community, maybe can help you:

https://community.cisco.com/t5/collaboration-voice-and-video/how-to-troubleshoot-one-way-no-audio-issues/ta-p/3164442

Regards 

[Jonathan Schulenberg]

If it only happens when using CIPC over VPN my suspicion would be protocol inspection of the firewall. Exempt the address pool from SCCP, SIP, and RTP protocol inspection.

Do not check MTP Required; it’s a crutch/bandaid that doesn’t solve whatever your real problem is. Modern CUCM versions, especially since 8.6, should almost never need to use this.

[Jason Bree]

I agree it has to be something on the firewall.  The odd thing is that it starts working 15 seconds into the call.  It also works immediately if I disable built in bridge.  

Thanks

Jason