Via header issues while talking to OCS Access Edge Server

Hi,

I am trying to use the Jain-SIP stack and the proxy to talk to Microsoft OCS. 

There is a peculiar problem I am noticing: when my proxy forwards a message 
(say SUBSCRIBE) to the OCS Access Edge server (AES) it adds the Via header 
with the SIP listener's IP, port, transport (e.g. 17.1.16.1:5061, 
transpost=tls). Note that it uses the listening port 5061 however when it 
connects to the AES as a client it has a different ephemeral port bound to the 
local socket. The AES records the ephemeral port as the port from which it 
actually received the message and because there is a mismatch between what the 
Via header says (port=5061) and the actual port, it decides that NATting is 
going on. Then when the AES needs to send another request (say NOTIFY) back to 
my proxy as part of the same dialog to (17.1.16.1:5061,transport=tls) it 
decides that because of NATting it should be using the same connection on 
which it received the SUBSCRIBE. However my Jain-SIP proxy closed the 
connection after receiving the 200 OK (to the original SUBSCRIBE) on that 
connection. The AES then barfs saying that it didn't find any open connection 
to send the NOTIFY instead of trying to open a connection to 
(17.1.16.1:5061,transport=tls).

I am not sure if OCS/AES is doing it right as per RFC3261 but how do I solve 
this problem? I am planning to modify the Jain SIP stack to use the actual 
ephemeral port in the Via header to make OCS/AES happy. Any other suggestions?

San