NO JOY One-way audio-transcoding issues

jackal

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Asterisk 13.13, Incredible GUI 12.0.39

At my wit's end here (troubleshooting this off and on for more than a month), so hopefully a post here will be fruitful.

Calls from extension 1 to extension 2 are fine. Calls from extension 2 to extension 1 result in one-way audio: extension 1 cannot hear anything from extension 2.

It's not a NAT issue. AFAICT it's something weird with the codec transcoding.

When extension 1 calls extension 2:

core show channel PJSIP/1
NativeFormats: (g722|ulaw|alaw|g729|siren7)
WriteFormat: slin48
ReadFormat: slin48
WriteTranscode: Yes (slin@48000)->(slin@16000)->(g722@16000)
ReadTranscode: Yes (g722@16000)->(slin@16000)->(slin@48000)

core show channel PJSIP/2
NativeFormats: (opus)
WriteFormat: slin48
ReadFormat: slin48
WriteTranscode: Yes (slin@48000)->(opus@48000)
ReadTranscode: Yes (opus@48000)->(slin@48000)


When extension 2 calls extension 1:

core show channel PJSIP/1:
NativeFormats: (g722)
WriteFormat: opus
ReadFormat: g722
WriteTranscode: Yes (opus@48000)->(slin@48000)->(slin@16000)->(g722@16000)
ReadTranscode: No

core show channel PJSIP/2:
NativeFormats: (opus|g722|ulaw|alaw|g729|gsm|ilbc)
WriteFormat: g722
ReadFormat: opus
WriteTranscode: No
ReadTranscode: No


Extension 1 is a Polycom VVX 411 that supports G.711a and G.711μ, G.729AB, G.722.1, iLBC. Extension 2 is a Groundwire softphone that supports Opus, G.722, G.711a and G.711μ, G.729a, GS, and ILBC, in that order. (All are enabled.) In situation #2 (when extension 2 calls extension 1), Groundwire shows a split codec ("OPUS/G722"), confirming it's a different codec for each direction.

Neither extension has any codecs in allowed or disallowed codecs in the extension settings. The SIP Settings page has everything enabled in the following order (excerpted, don't want to list the entire list): opus, g722, ulaw, alaw, g729, gsm, g723, g726, etc.)

(Opus is my preferred codec where it is possible to be used.)

Any ideas where to go from here?

If I can get this fixed and finish getting AvantFax working with T38modem, I'll have a fully-featured, bulletproof PBX that I'll never need to ask another question on here about again. I hope. ;)
 
Last edited:

krzykat

Telecom Strategist
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When troubleshooting, I like to simplify things as much as possible. You hypothesize its a codec issue. I'd try using SIP instead of PJSIP and allow only G.711. That will use the more standardized method and eliminate your transcoding question. If that works, start opening it up, I'd probably change the order of SIP to match what you've got, and after that try the PJSIP.
 
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