Hi,

I am thinking about having more NAT test on a sip packet. Just want to find out if it is useful.

I run into some situations that some ‘smart’ UAs try to detect its external IP and put the external IP address into the sip packet. Depending on the network and NAT firewall setup, it may or may not set the right external IP and port in the packet. If it is not, but pretends to be on the public internet, then there is most likely a one-way voice or no voice issue. I’d like to be able to detect and force it to use a nat proxy. By checking these packets, I found that the only trace is the private IP address in the call-id header field. It will be useful to check if a RFC1918 address is used in the call-id. I understand that it is not a thorough test for NAT, well, just like any other NAT test.

Can someone please comment if it is a good test?

Thanks,

Richard