[SR-Users] SUBSCRIBE/NOTIFY record route

[Spencer Thomason]

Hello all, 

I'm using Kamailio (on a public IP) as a border proxy
that handles NAT traversal (detection and keep alives) for several
Freeswitch servers which have public IPs as well. I'm having a problem
record-routing SUBSCRIBEs and NOTIFYs for nated UACs. If the UAC is
behind NAT, I am adding a Record-Route to the initial SUBSCRIBE and
NOTIFY request. This works great until the UAC (in this case a Cisco
SPA509G) refreshes the subcription and sends the SUBSCRIBE directly to
the Freeswitch server. Since the request doesn't pass through the proxy,
Freeswitch then sends NOTIFYs directly to the UAC which only recieves
the first NOTIFY as the NAT pinhole is still open from the SUBSCRIBE.
The UAC did receive a NOTIFY validating the subscription, and continues
to refresh the subscription directly to the freeswitch server. The
completely breaks presence. 

What is the correct way to ensure all
SUBSCRIBE/NOTIFYs pass through the proxy? I have found that I can force
this behavior by modifying the Contact header in the 202 Accepted to
point back to the proxy but I'm not sure if this is what I "should" be
doing. 

Thanks for any assistance and please forgive my ignorance when
is comes to SIP presence! 

Spencer 
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