Is there any way to see if a SIP message is from behind nat? The example for nathelper searches for Cisco ATA, but you could have that without nat and you could have a different phone behind nat. Can I always apply nat fixing? Does it break anything if it was not natted? (My SER is not behind nat. It might make a difference if SER itself is behind nat.)
Is there still (0.8.11) the function add_rport()? SER does not complain with it there. Is it the same as force_rport? Does it do anything? Is it necessary? What does it do? (I see force_rport in nathelper.cfg.)
Why would I want to add direction=active?
Am I correct that there are 2 points in a SIP message that there could be problems from nat, 1-various SIP headers, and 2-SDP (c=, o=)? Does fix_nated_contact fix everything in the SIP message itself and fix_nated_sdp fix everything in SDP? Where would I want fix_nated_contact and fix_nated_sdp? Do I want fix_nated_contact in every message and fix_nated_sdp in INVITEs and its responses (provisional and OK)?
Thanks.
Dovid