PBX delivers audio when using an SBC

[Rob24h]

Hi guys,

Will enabling the option "PBX delivers audio" still help when the customer is using a 3CX SBC and the PBX is in the cloud?
Enabling this option has helped resolving issues before when using a PBX in the cloud but i'm not sure if it will help when the customer is using the 3CX SBC?

 

[YiannisH_3CX]

Hello @Rob24h

What is the issue you are facing? Generally speaking PBX delivers audio should not be enabled when the phones are behind an SBC as all traffic will be redirected to the PBX. When the option is off, extensions behind the same SBC can talk directly between them once the call is established. With the PBX delivers audio on this is not possible as all audio will be redirected through the PBX.
We will need to know the issue though to know if you need to enable the option or not.

 

[Rob24h]

We're experiencing audio issues with external calls and transfer issues with internal calls.
Phones are Yealink T40, PBX is 15.5 latest update.

 

[YiannisH_3CX]

Are the phones running the latest supported firmware and are provisioned with the default templates? You can enable the option and test if that helps with the issue. You can also provision a 3CX client on the same site that connects using the tunnel and see if you are experiencing the same issues.

 

[Rob24h]

Latest firmware and default template indeed.
I will try and test it but is there somewhere a description as to what exactly the 'pbx delivers audio' function does?

 

[leejor]

If you are having issues with external calls, then the audio is probably routing via the PBX anyway, and there may be another issue, (or option?), causing the problem. When using remote extensions, 3CX will normally try to establish calls directly between the extensions, but without the SBC, an extension is "seen" as PublicIP & port, not the local IP & port of each device. Trying to connect two remote devices with this is information, and(perhaps) the limitations of the local router, can cause audio issues, usually, a total lack of. Using "PBX delivers audio" simple routes all voice packets back through the PBX, for extension to extension calls. Not the most bandwidth friendly, not to mention an additional strain on the PBX processor, if that is a concern. The SBC keeps track of local calls making use of the local IP and port of each device, sending all voice packets direct from one set to another.