OPUS codec support and usability in v15.5

[PierreM]

I have lots of questions about OPUS.
Yesterday a colleague in the office told me that I sounded amazing on the phone, as if I was right next to him.
They were in a conference room using a Yealink CP960 and I was using the 3CX Webclient from home to dial-in into the meeting. I also experienced from my office phone (Yealink T42s) a great quality call and on my phone display, I saw the letters "HD". So these 2 experiences tell me that I must of been using OPUS...right?

So here are the questions:

1. I haven't found a place in the settings of the webclient where I can see which codec is supported or used. Does anyone know where I can find that info?
2. The settings in the APP on my iPhone has a bunch of codec listed, including OPUS, but OPUS was not selected, so I selected it? BTW, there was about 5 different codec selected. So how does the APP determine which codec to use?
3. I really would like to at least use OPUS internally when we call each other's extension. Can this be forced or suggested as the preferred codec to use in the phone system config?
4. When making an outside call from my office phone, what determines the codec that will be used to complete the call to someone in another country? Is the audio codec selection part of the initial call handshaking negotiation?
5. Do long distance carriers and SIP trunking carriers have to specifically support the OPUS codec or do they pass through any traffic, irrelevant of the codec used? Our phone system hosting vendor uses Bell Canada for its SIP trunking needs.

Thanks
Pierre

 

[cobaltit]

HD is generally for G.722. I don't know that it shows that for OPUS. And my understanding is that the T4X templates have not been OPUS enabled yet so I doubt you were using OPUS unless it was manually configured. As far as your questions:

1. Don't know, haven't looked
2. The selected codecs are ones that are supported. Generally both ends of the call will support several codecs and prioritize them. The two sides negotiate the highest priority common codec for the call.
3. OPUS can be selected as the highest priority codec on a per extension basis for those phones that support it in the official template. For phones that 3CX has not added/enabled OPUS support in the template they would need to have it manually selected in the phone or via use of a custom template.
4. There are effectively 2 legs to that call that you have control over; your endpoint to the PBX and then from the PBX to your provider. I don't know of any provider that supports OPUS on their SIP trunks. While some may have the ability to do that it's generally not offered because as soon as the call goes off-net (to the underlying carrier) they pretty much only support G.711 so it's not worth taking the hit on the transcoding. This is true for us as we can do OPUS on-net but anything that goes off-net is only negotiated at G.711 because our carriers don't do OPUS.
5. Basically yes.

Long story short OPUS is great for your internal calls to realize some bandwidth savings, higher quality (or both) but realistically I wouldn't expect to see OPUS being used end to end for several years.

 

[YiannisH_3CX]

Hello @PierreM

I will try to answer the first point:
The web client uses WebRTC and basically uses the same codecs as WebRTC. You can open a new tab in chrome and type "chrome://webrtc-internals/"
While making a call this will provide all the information you need.

 

[B.Fluehmann]

@YiannisH_3CX
Thank you for the hint to "chrome://webrtc-internals/"
Since we have a mixed experience with webclient audio quality I have started a debug session with it.
What I have figured out so far is that the call leg of the caller uses opus and the call leg of the callee uses PCMA (g.711Alaw). This means the pbx is transcoding what explains the choppy voice. In the meantime I have tried with different codec settings but the behavior is always the same, which means as well that codec settings have no effect on Webclient.

Please let me know how we can get this fixed or what kind of information you need to analyse and reproduce the problem.

Regards
Benhard