Use different audio codec for internal and external calls

[Average_Joe]

Is it possible to specify a codec order for internal vs. external calls? For example, I would like to use G722 for extension to extension calls but G711u for external SIP trunk calls.

My SIP trunk provider does not support G722. I tried having my extensions use G722 as their primary codec but then there is a noticeable audio quality degradation when placing a SIP trunk call which I believe is due to 3CX transcoding to/from G722/G711u. Extension to extension calls are better when using G722.

For our tests we are using the 3CX Windows client.

(I apologize if there is another thread that specifically addresses this. I spent a while reading through similar topics but didn't see one that quite satisfied my question.)

 

[leejor]

It sounds as if you desire the behaviour in the "example", in this post. Note the options mentioned.
https://www.3cx.com/community/threads/disable-transcoding.61461/

 

[eddv123]

See under:
Settings >> General


You have priority for local/internal and external here that you can set. My advise normally is to have G711 for your internals and then a compressed/less bandwidth hungry codec for external (if your provider supports( G729 and/or iLBC) are good examples of these types of codec.

You will also notice that codecs can be set per extension and per trunk also.

 

[JohnS_3CX]

Hi,

If you prioritise G.722 on the phones, and the PBX internal calls, the leg of the call between the PBX and the phone will be G.722, but the leg of the call between the trunk to the provider will always have transcoding to G.711 to avoid a no-audio situation (as per trunk settings).

You will likely have transcoding take place in all scenarios that include external calls (incoming and outgoing). Your internal calls however will sound better due to the clarity of G.722

Note: In addition, even if the provider supported G.722, this does not mean that the other party will. The provider will likely have to transcode for you anyway for most cases.