SER doesn't seem to be returning the Unauthorized message to the correct port, but it does get at least the right IP. You will notice the REGISTER is received on 216.43.27.75:56059 but the Unauthorized is sent back to 216.43.27.75:5060. Is there any way to get SER to send back to the correct port so symmetrical NAT will work correctly?
Yes. Use Nathelper/RTPProxy.
Andres Network Admin http://www.telesip.net