Hello Community,
I am facing a massive wall trying to route incoming calls to an on-premise PBX (Grandstream UCM) using the local SIP-TA (B2BUA) feature on a Centro Business 2.0 router running a beem Office profile.
Current Setup Status:
The Grandstream PBX is in the local network.
The local SIP-TA account has a strict password compliant with Swisscom rules (only lowercase, numbers 1-9, no 0, no ‘l’, etc.).
The Trunk status on the PBX is Registered, targeting the Centro gateway.
Outbound calls work perfectly through the PBX.
The Problem: Incoming calls completely fail. Whenever our business number is dialed, the Centro Business 2.0 seems to intercept and silently drop the incoming SIP INVITE packets instead of pushing them down to the successfully registered local SIP client.
We have already physically unplugged everything from the router’s analog RJ11 ports, and the inbound route on the PBX is using a wide-open catch-all (_X.) pattern to ensure it accepts any incoming number string, yet the call never even hits the PBX logs.
It looks like the Centro’s internal firmware routing is “stuck” trying to reserve the number block internally or blocking the local forwarding loop because of the beem Office cloud profile profile.
Has anyone successfully resolved this inbound invite drop issue on the Centro 2? Is there a hidden flag that second-level support needs to toggle on the backend to completely release the number block to the local SIP-TA users?
Thanks for any insights!