Solved Codec settings in multiple places

[DaveB-Opt]

Sorry if this has been asked before.
I notice that there are codec options under the SIP trunk configuration, as well as for each extension.
Which setting takes preference?
Thanks

 

[ChrisC_3CX]

They are two different things, the codecs on the extension level will define the codecs to be used by the endpoint (IP Phone, 3CX Client) when communicating with the PBX, and the codecs on the SIP Trunk level will define the codecs used by the PBX when communicating with the SIP Provider.

 

[DaveB-Opt]

Thanks - so as I have PBX delivers audio unticked, I'm only concerned about the SIP trunk codes?
Or will the extension level codecs be applied to internal calls?

 

[ChrisC_3CX]

First off, PBX delivers audio will not affect calls connected to an external number as the audio in that case always goes through the PBX. It will only affect internal calls such as a call between two local IP Phones.

Regarding the codecs, which codecs will be used and in which priority depends on a number of things such as, if it's an external call, who initiated the call, what the 3CX Endpoint is (IP Phone, 3CX Client), where the 3CX Endpoint is and how it's provisioned, etc.

What is your scenario, are you facing a specific issue?

 

[DaveB-Opt]

Thanks for the reply.
Our internal calls are crystal clear.
Our external calls are often a little 'crackly'. 3CX runs on a Hyper-V VM with plenty of RAM and CPU power. We never have any more than 2 simultaneous calls.
I've set the codecs to be 711, 729 & 722 in that order on both the SIP, and the extensions (mainly Windows and Android apps).
It's intermittent. The other day I tested 3CX to a mobile number and it was fine.
This morning I've called 2 external numbers from the same 3CX app and there's a little interference/crackling.

 

[ChrisC_3CX]

Since Internal calls are fine, I see no reason in modifying your extension codecs just yet. You could change your SIP Trunks codecs order but since the issue is intermittent, it might not be related to the codecs set on 3CX at all. I would first recommend using a 3CX Supported SIP Provider if not using one already, and also contacting one of our 3CX Partners to help you troubleshoot the issue in-depth.

Just bear in mind that since you're talking about an outbound call from an extension set to use the same codecs as the SIP Trunk, it is very likely that the codecs used for both the internal and external call legs were the same, meaning that no transcoding was being done by 3CX, meaning that less processing was required.

 

[DaveB-Opt]

Thanks - we do already use Gamma who are supported.
I'll contact them as it's completely random.