Phones Not Registering

[RTSB]

We are deploying a 3CX system, internally hosted, and I cannot get the phones at my remote branches to register. I have a router at each branch giving out DHCP, routing works correctly between sites, DHCP works at each site, except the phones at the remote branch will not register. Any ideas of where to look would be helpful.

Thanks,
Stephen

 

[Pratt]

Are you using STUN or an SBC at the remote location

 

[JohnS_3CX]

Hi Stephen,

You should install an SBC at each remote site to help your phones connect to the PBX.

The SBC can be installed on anything from a Raspberry Pi, to a spare PC, to a VM. The only requirement is that the SBC is running on the same network as the phone so they can see each other.
https://www.3cx.com/docs/3cx-tunnel-session-border-controller/