SIP Request rejected. Reason: Block WAN Requests is on.

[Jabii Romea]

We're trying to provision an extension into a physical phone, however, we keep on receiving SIP Request rejected.
Reason: Block WAN Requests is on.

To make it clearer:
We have 2 sister companies with 2 different domains and 2 different 3cx servers hosted in lightsail. Both of their offices are under 1 external IP Address.

So in a clearer picture its:
- CompanyA has 3cxA; CompanyB has 3cxB
- We want to provision a phone from CompanyA to CompanyB but 3cxB says SIP REquest rejected. Reason: Block WAN Requests is ON.

We want to be able to register an unused phone from whichever company so they can just have 1 list of unused phone for both.
How do I do this?

 

[bitn2]

You need an SBC or routerphone.

 

[KyriacosS_3CX]

You need an SBC or routerphone.

Well, he needs 2 SBCs or router phones really

@Jabii Romea, if not familiar with SBCs, here's a starting point: https://www.3cx.com/docs/3cx-tunnel-session-border-controller/

With your scenario anything else will quickly become too complex to manage.