Hi, I'm sure everyone is tired of NAT related questions, but I am really struggling here :( I have freeswitch configured on an EC2 instance, with an elastic IP address. I've followed all of the NAT configuration instructions on the EC2 wiki (http://wiki.freeswitch.org/wiki/Amazon_ec2) and have researched widely on other possible solutions to no avail. Most scenarios work fine, but I'm having issue with one particular call path (see scenario 4 below). Firewall is correctly configured on the EC2 machine. Scenario 1: x-lite to x-lite - Both clients running behind firewall/NAT - Voice path in both directions Scenario 2: x-lite to PSTN - x-lite running behind firewall/NAT - PSTN is connected via SIP-trunk from Freeswitch to VoIPon ITSP - Voice path in both directions Scenario 3: PSTN to PSTN - Both endpoints connected via SIP-trunk (VoIPon ITSP) via Freeswitch - Voice path in both directions Scenario 4: PSTN to x-lite - Exact reverse of scenario 2 - Voice path one way (PSTN to x-lite) Is there something obvious that would prevent this specific scenario from working? I've dumped a SIP trace for the fourth scenario onto pastebin... http://pastebin.com/dg1XqxsJ I'd really appreciate some assistance and guidance! Kind regards, Sara