Didnt get any response from the mailing list, so reposting it. Please do
reply if you have any clue.


Hi,

I am running Windows Messenger Clients V 5.1 (SIP Communications Service
enabled) on etiher side of my SIP proxy. They can do presence, voice
calls, whiteboard, application sharing, BUT cannot do Instant Messaging.
I tried with few other SIP Proxies, but they too cannot do IM.

When I analyzed the network traffic, I found that the sender sends a SIP
INVITE and the receiver sends a SIP OK in reply. But immediately,
afterwards the receiver sends a SIP BYE message to terminate the dialog.
Thus, the SIP MESSAGE message from the sender couldnt reach beyond the
proxy as there was no corresponding active dialog.

I have no security issues as I have turned off EnableHighSecurity
option. I have disbaled my firewall. Also there are not NAT issues, as
both the clients sit in the same network.

I observed this issue with WM 5.0 also but not with WM 4.7 as WM 4.7
doesnt send a SIP INVITE to initiate the dialog.

Please help.

-Prashant