CODEC Order

[gustavo.loureiro]

Hi,

I'm trying to improve call quality and one of the points is trying to avoid transcoding.
I noticed that calls are transcoded by looking at the quality monitoring report:



My question is: where do I set up CODEC priority besides the places below so that my PBX uses the same CODEC as the provider, in this case, G729?



and


I have 3CX V20.0 Update 3 (Buid 659) on premises.

Thanks in advance.

 

[NicholasP_3CX]

This is where you make the changes, nowhere else is necessary. The apps will need to be restarted after the change to the codecs.

 

[gustavo.loureiro]

Thanks.

Ok, now I can see a couple of calls where our 3cx appliance and the service provider both agree on the CODEC.

However, the call is still transcoded



Am I missing something?

Again, I'm assuming call transcoding should be avoided for a better, clean experience...

 

[ivank]

If the call is recorded or "PBX Delivers audio" is on or SIP trunk doesn't support reinvites, the transcoding mode is enforced regardless of the codecs.

 

[gustavo.loureiro]

If the call is recorded or "PBX Delivers audio" is on or SIP trunk doesn't support reinvites, the transcoding mode is enforced regardless of the codecs.

To start with, the call is recorded (and must be).
Thanks

 

[ivank]

Also note the substantial packet loss from Asterisk towards 3CX on the last screenshot: 4% will be very noticeable on the receiver's (i.e. 3CXPhone) side.

 

[gustavo.loureiro]

note the substantial packet loss from Asterisk towards 3CX

Yes, I noticed that.
I'm currently tackling possible latency issues on both sides, but it's not easy to deploy a reliable measurement method, specially on the Internet.
I'm already using limiters on the pfSense edge router, which noticeably reduces bufferbloat, but our current latency measurements still show undesirable spikes.
I'm still studying more solid measurement methods, like Round-trips Per Minute (RPM) (here and here), flent, and how can I use queue management algos like cake or pfSense limiters.
But I digress...