media path between phones behind different SBCs

[coreybrett81]

Hoping someone can save me some time with Wireshark... ;-)

With default 3CX settings and a supported phone:

Will media travel directly between phones when both phones are behind the same SBC?

When phones are behind different SBCs? (branch offices)

I know there is an ext setting that forces all media via PBX, but I'm leaving that disabled.

 

[eddv123]

Hi Corey,

Same SBC - the audio will stay local to the phones (point to point), unless the aforementioned setting is enabled.

This is part of the reason for the SBC, so that the media does not have to traverse the remote PBX and add extra latency and strain onto the PBX itself.

By different offices, branch offices I just want to confirm you mean completely different sites or same site with multiple SBC's (which is supported) and would be an interesting question.

 

[coreybrett81]

Each branch/site will have it's own SBC. Server will be with a cloud provider.

 

[eddv123]

OK this is where I am afraid I cannot answer with 100% confidence but I will give my opinion.

I think that as each site is in a separate network each connected to the PBX via its own SBC then the handsets must forward the media stream via the PBX before traversing to the other site.

I cannot see how the media path could go directly between sites (endpoint to endpoint) as the phones sit behind the SBC and are not internet facing.

I would be keen to hear if anyone else has anything they can add.

 

[dandenson]

I've tested this already. data flows as you suspect:

Site A SBCA
Site B SBCB

Phones on site A connect via SBCA
Phones on site B connect via SBCB

Phone A1 to Phone B1 will do this:

A1 > SBCA > 3CX > SBCB > B1

This is where an enhancement to the SBCs would be nice, have the SBCs peer together.

My test scenario was actually a single site with 2 SBCs with a roughly 50/50 split for load balancing. If even number phones are on SBCA, and odd numbered phones on SBCB, then an even to odd call goes up to the PBX.

 

[coreybrett81]

okay, I will have routing between all branch offices, but I wasn't sure if the phones from different subnets would try to connect directly or not

I'm tempted to force all extensions to send audio via PBX so that their is no random behavior

 

[YiannisH_3CX]

okay, I will have routing between all branch offices, but I wasn't sure if the phones from different subnets would try to connect directly or not

I'm tempted to force all extensions to send audio via PBX so that their is no random behavior

Please note that the audio will stay local only if 2 extensions are provisioned behind the same SBC. If the extensions are not using the same SBC then the PBX will handle the audio. If you want to avoid unnecessary traffic to the PBX then i would recommend leave the option "PBX Delivers Audio" unchecked.