SIP - Call forward to external, No audio

[tijuanach]

We just recently moved to SIP (last week). Today, I noticed a problem with call forwarding. For example, I called three staff members' office phones (internal) on my cell phone (external). All 3 staff members have calls forwarded to their cell phones (external). The calls are connecting, but there is no audio. I can't hear them and they can't hear me. 

[Flavio Miranda]

Hi

 If the calls got connected then SIP did his job. No audio might RTP problem. 

[Oleksandr Yurchenko]

Hi,

What does mean- "moved to SIP" ?  Do you change conection to ITSP ?

Do you know what is infrustruction you use ?

BR Oleksandr

[tijuanach]

PRI to SIP conversion. 

[Kaloyan · Accepted solution]

Without logs, we are just guessing. Here's the most common problem with the scenario you described https://community.cisco.com/t5/collaboration-voice-and-video/troubleshooting-no-audio-issues-on-hair-pinned-calls-on-the-cube/ta-p/3676035

I recommend the media anti-tromboning https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/media-path.html.

[tijuanach]

Thanks @Kaloyan! Your recommendation (media anti-trombone) resolved the issue for us.