IAX Between 2 PBX ( One NAT One No NAT)


I have just completed the connection of 2 PBXs via IAX2 trunk. Here’s the setup:

CloudPBX is on a public IP on the internet.
PBX1 is behind a NATing device with dynamic IP (home use internet connection)

Now, I understand that the IAX trunk has 2 ends (one from PBX1=>CloudPBX, and the other is CloudPBX=>PBX1).

The thing is, CloudPBX can not connect to PBX1, the IP keeps changing.
But, PBX1 is able to connect to CloudPBX successfully.

Would the trunk work only on one leg? I mean, will I be able to make calls from both boxes if only PBX1 registers on CloudPBX? OR both ways should register?

Also, if only one leg is enough (PBX1=>CloudPBX), so how would I set the dialing string (IAX2/TRUNK_NAME/EXTENSION)? What should be in place of "TRUNK_NAME?

Use registration on the nat side. At the cloud PBX set the host setting to dynamic.

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Thanks for the quick response. Shall I have port 4569 forwarded on the NAT side to the internal PBX? Right now there’s no port forwarding on the NAT side.

You shouldn’t need port forwarding, but it depends on how poorly behaved your router is. Use a registration string of the format:

 username:[email protected]:port

Thenks for the info. On the CloudPBX, I see it accepts registerstion of PBX1, and detects the public IP of PBX1.

But, it says: unreachable. Im not forearding any ports in the NATing gateway.

Set at the cloud PBX qualify=no at the peer settings and try to call.

Still no good. Same thing.

The registration string is on the incoming side of the trunk config. So shall I put that on the CloudPBX incoming? Or the PBX1 incoming?

I put that string on the PBX1 incoming side. And still the issue exists. Still Im not doing any port forwarding.

At the nat site do you have qualify setting in your peer details? If yes try setting to lower frequency to keep the communication open between the two sites.