Hi all. I've been trying to get 3cx to work for incoming calls on our DIDs with our trunk provider. most of the kinks are sorted out except for one. I can make outgoing calls fine. I get audio on both ends. On my incoming calls however I only get audio from the callee (outside) and the audio on our internal phones(connected to a local 3cx PBX) does not get sent out. IE if someone phones me I can hear them - they cant hear me. I have narrowed it down to the way TMG deals with sip/rtp. it seems to be randomizing the outgoing port. I was wondering if we could use the 3cx SBC on our DMZ network to tunnel the trunk through to our internal 3cx PBX. not only would this be more secure (as the internet would never actually see our internal network or PBX) but it would also solve the problem with other firewall solutions that have a similar problem (ISA and sonic wall I'm looking at you!) Any help would be greatly appreciated.