I appreciate this question is quite "out-there" but – has anyone had any success with VOIP over SIP behind a SonicWALL. We are having an issue with one-way audio inbound.
Essentially, the person calling (or called) can hear me (from the phone on the same LAN as the PBX), but we cannot hear them. Packet captures show the RTP traffic coming back to the Sonic and destined for the PBX but it simply cannot be reaching it. My understanding is SonicWALLs use Symmetric NAT and this is the problem as STUN doesn't work with this type of NAT.
Is there any workaround or anyone here with any success?
Best Answer
If it's a sip trunk, you may be able to get away with telling your PBX its IP is your "external" IP, and forwarding tcp/5060 and udp/[rdp range] to it in the sonicwall. The rtp range will be configurable in your pbx. Because you only need one sip endpoint (the pbx - all your phones talk to the outside world via the pbx) this shouldn't require stun or anything "clever".
It sounds like you already have the first bit done if the rtp traffic is really reaching your sonicwall, and not just landing in a blackhole because it is being sent to an rfc 1918 address.