I have an IP Office IP500v2 behind a Watchguard Firewall. The IP Office is running R8.1. I periodically am getting one way audio or dropped calls because the IP Office seems to be changing the port from UDP 5060 to random port numbers usually in the 1200 or 1300 range. I have the Firewall type set to Static Port Block but have also tried using Full Cone NAT. has anyone seen this behavior before or know how to resolve this?