Sorry about that: Network Topology. 8.21.8.24 is the PSTN gateway (WAN IP) 192.168.2.5 UAS (simple IP phone, "PC to PC" no registrar, etc) 192.168.2.1 NAT Router with 192.168.2.10 in DMZ WAN Address is 2.6.7.9 in my previous message. 192.168.2.10 OpenSER and RTPProxy.