VoIP access from external WAN to device on Untangle

[kenatcomtex]

I have an NEC phone system which has a mobile app that can be used from off-site to access the phone system. It's a simple SIP client. The phone system requires a connection on port 5070 to one IP address and wants voice traffic passed to ports 10020-10147 UDP to a second IP address.

I have port forwarding rules in place for those (Protocol: TCP Destination Port: 5070-5071 -> IP of phone system, Protocol: UDP Destination Port: 10020-10147 -> Second IP of phone system for voice traffic).

I am able to get the phone app to connect but I get no audio.

If I set a NAT rule in Networking -> NAT rules for all traffic to the voice ports, I still get no audio. If I set a NAT rule for all traffic to the phone system IP address, I get ringing but no other call control.

I have tried setting up Bypass rules and access rules. SIP NAT helper is turned off. From what I've read, that is essentially SIP ALG and my setup documents say to have it turned off.

Any ideas?

[sky-knight]

You need to hit your documentation, I've never seen a PBX split SIP and RTP traffic. The no audio thing means RTP isn't making it to the correct place. The SIP port itself must be correct, or else the remote phone wouldn't connect at all.

So I'm left to assume your RTP range forward needs adjusted to aim at the internal IP address you've forwarded 5070 to.

[kenatcomtex]

It's actually more common in hybrid systems. This system has a separate interface that handles the voice traffic. It's a virtual interface but it is still defined in the system with a completely separate IP address.

[sky-knight]

And I support a ton of different hybrid systems too, but in my experience that virtual NIC isn't there to split off the RTP, it's there to split off management.

If you an register, but not make a phone call RTP is screwed up. That can mean the forwards are wrong, that can also mean the PBX isn't configured to know that session is from outside the network and is failing to perform NAT correction.