Increase in PBX traffic after turning OFF "PBX Delivers Audio" for SIP Trunk

[poynter]

Have 3CX in Azure with SBC onsite.

Previously the SIP Trunk was set as "PBX delivers audio", turned this off to decrease the amount of traffic passing through the PBX, but it's actually doubled the amount of outgoing traffic. Any ideas why?

Highlighted point is when I made the change, no other adjustments or increases in phone calls.

 

[leejor]

You may need to use Wireshark to see exactly how a call, to a trunk is established. Since the sets make use of an SBC, and the SBC makes use of a port going to the PBX, I question how a call from a set would be sent direct to the IP & port of the SIP trunk, without going through the PBX. I may be missing something, but bypassing the PBX, set to set, is pretty straight forward, if not forcing PBX Delivers Audio, but to a SIP trunk, and through an SBC, not so much. As to why it increased rather than simply staying the same...can't say, but someone from 3CX might be able to explain it.. I'd change it back for the time being, if you haven't already done so.

 

[YiannisH_3CX]

Hello @poynter

Please note that when a call goes through the SIP trunk in the majority of the situations audio will route through the PBX regardless if the PBX Delivers audio is enabled or not. The option should be enabled by default in all trunks to avoid an edge scenario where the PBX will not process the audio streams. If that happens then you will probably not have audio in calls which is never good. So it should make no difference in the traffic that goes through the PBX if the option is on or off.