Extensions at remote site unable to call each other

[kaiserh]

I have a 3CX system across two sites. Most people use the mobile app, there are only four desk phones.
3CX is running on a NUC at Site A where there is also one physical handset.
At Site B, there are three physical handsets, but no SBC or anything else like that.
Just in case it matters, all four phones are Yealink SIP-T43.

At Site B, in Phone Provisioning, all three phones have different Local SIP Port and a different range for Local RTP Audio Ports.
For example:
Handset 1 - Local SIP Port 5065, Local RTP Audio Ports 14000 - 14019
Handset 2 - Local SIP Port 5066, Local RTP Audio Ports 14020 - 14039
Handset 3 - Local SIP Port 5067, Local RTP Audio Ports 14040 - 14059

Under rights, all four phones (Site A + Site B) have Can intercom enabled.

When they pick up Handset 1 and dial the extension for Handset 2, they can't hear anything.
Calls between the desk phone at Site A and any of the desk phones at Site B work as expected.

Any idea what's going on?

 

[Alphabetic]

Do you have "PBX Delivers Audio" enabled?

 

[kaiserh]

No, I'll try enabling that for the three remote extensions at Site B.
I wasn't 100% sure what this setting does (it routes audio through the PBX) or if it would make a difference.
Thank you.

 

[Alejandro_3CX]

Hi @keiserh please note that remote deskphones must be provisioned with the 3CX SBC or behind a router phone.

STUN is not a supported provisioning method nor recommended.

Please try to configure the phones as mentioned in the guides and using the supported firmware and template.

Have a great day.

 

[SteveITS]

Yealink SIP-T43

If it's a 43U it can be a router phone. Just delete, factory reset, and reconfigure one for that, and the other two can use it as their SBC. All port forwards (and issues) go away.
https://www.3cx.com/sip-phones/yealink-t4-series/