Hi

We have a Mitel CS-5200 and have configured NAT to allow softphones to connect outside the network. The phones connect ok and can successfully make calls to other extensions. When we dial external numbers, the call rings and connects, but we don't get any audio - either way.

I would appreciate any ideas

Thanks

Cammy

An IP trunk uses a B-channel and a D-channel. The D-channel is usually TCP packets and they "nail up" the call. The B-channel is usually UDP packets, and carry the voice.

So, if the phones make calls internally OK, then the phones themselves are OK; and if it can nail up a call, then the TCP portion is OK.

I'd check the router or firewall to make certain that UDP packets are allowed to pass through. A good resource is the "leaktest" utility found at www.grc.com : https://www.grc.com/lt/leaktest.htm

Thanks

I only had 5567 udp open outbound previously. Temporarily allowed any outbound udp which seems to have fixed the issue. Why are the required ports not listed in one of the myriad of manuals?!

Cheers

Cammy

Good question. I believe that I have seen integration sheets from Mitel which spell out the required ports, but for some reason they tend to be a bit obscure.

It may have to do with the way that Mitel conducts training and certification.

Glad that helped.