Codec Advice

[JDawson]

Hey guys,
I am looking for some advice on what codecs setup may be best. I have had the customer say the voice quality is not that good. I left the standard settings and wondering if there might be a better setup.

Customer setup
3cx windows on a local machine at the customer's premise
internet connection is 100mbps down and 25mbps up
handsets 25 Yealink T46S (a big chunk are in meeting rooms and won't be used most of the time).

I believe that adjusting the codecs may help but I am a bit lost about what setup might be best.

So I can run some tests can I check what codec has been used on each call via logs?

 

[Alphabetic]

What is your network topology? How many devices? got a fancy switch you've misconfigured?

Can you replicate the problem?

Is it all calls? (Internal calls/external calls)

I havent had a phone system that's come out the box and give audio issues unless the network was the problem.

Run the firewall test.

Give these a read:

https://www.3cx.com/docs/sip-trunk-codecs-sdp/

https://www.3cx.com/blog/docs/bandwidth-utilised-for-voip/

Change codecs and reprovision phones once you've done that.

Check with your SIP trunk provider what codecs they're offering too.

 

[leejor]

I would go with a Codec that is supported by your provider, to prevent 3CX having to do transcoding. If supported (again, by your provider), and you have a reason to do so (bandwidth issue), then try a low bit-rate Codec, otherwise go with G711 a or u, whichever is used in your region.

 

[SteveITS]

When adjusting codecs, remember to set codec order in 3 locations:

• SIP trunks
• Settings/General (internal and external)
• Each extension (for each phone on the extension)

 

[FridayIT]

I would go with a Codec that is supported by your provider, to prevent 3CX having to do transcoding. If supported (again, by your provider), and you have a reason to do so (bandwidth issue), then try a low bit-rate Codec, otherwise go with G711 a or u, whichever is used in your region.

100% do this, this will save you lots of pain and frustration, as well as cpu performance

3cx has rules for internal and external codecs.... but they haven't worked well in my experience.

 

[ts100]

I would agree with SteveITS, making sure you have confirmed the codec in the 3 locations mentioned would generally solve the issue. I was having the same issue recently and the difference was night and day.

 

[SteveITS]

I was having the same issue recently and the difference was night and day.

Yep. It would be great if 3CX had a way to set a default codec order for phones but it doesn't seem to. And the bulk editing of extensions doesn't allow for editing phone codecs (just "3CX App"), presumably because it can't know what phone model is attached to the extension and what codecs it supports.

Note also that PCMU is the same as G.711 U-law, and PCMA is G.711 A-law, depending on what page you're looking at in the console.

And yes ideally use ones supported by your SIP trunk provider as mentioned.

The web client uses Opus for outgoing calls.

 

[ts100]

A little automation in 3CX would go a long way, especially when changing the same setting on 100's of extensions, it gets tedious.

As we are in UK PCMU is the preferred, having said that we have used OPUS on our SIP Trunk provider.

 

[AWS2P]

you can set opus first but if no one use it and first position your sip provider then this setting is not really interresting.
IMO best is always to stick to SIP provider preferred codec order

 

[ts100]

OPUS is the preferred codec with our provider

 

[AWS2P]

so you can try in first but SIP has two ends so if remote is not able to use opus as G711 is most common over the world , then opus is perhaps good for internal calls only

 

[JDawson]

Yeah cool. I checked the SIP provider and changed it to a codec that they offer. I'll see if that makes a difference. That you all for your input