[Sip-implementors] SIP and Windows Messenger 5.0

[Zack Radick]

I have noticed that the Windows Messenger 5.0 client expects to receive an 
INVITE message before it will accept a MESSAGE message from another 
client.  This is a bit problematic, as it is not how many other clients 
behave (even Windows Messenger 4.7 does not do this).  However, in lieu of 
just complaining about it, I'm trying to get around this behavior.

I am working on an application that acts as a SIP Proxy (sort of).  It 
allows clients to register, but not to see each other or relay 
messages.  The point of the server is that clients should be able to 
connect to it and receive periodic messages from the server when certain 
criteria are met, but nothing else (of course there are a myriad of easier 
ways to do this than using SIP, but the CEO of our company wants it to 
support Windows Messenger).

I have had good luck so far with everything I have tried (Windows Messenger 
4.7, NIST SIP Client) except for Windows Messenger 5.0.  For some reason I 
cannot get it to respond to the INVITE messages that I send it, and it 
ignores all MESSAGE messages that are sent outside of a session (it 
responds with 100 Trying, followed by numerous BYE messages).  I'm not sure 
if the problem is that I'm trying to send an INVITE message from the Proxy, 
or if it's just something silly that I'm missing.  I have created several 
tools for testing this, but have yet to get a response to any of the INVITE 
messages I have tried to send it (though I have intercepted INVITE messages 
it has sent and simply tweaked them a bit and sent them back).  If anyone 
has worked with (or around) this issue, I would definitely appreciate some 
guidance.  I am a decent Java programmer, but a relative newcomer to SIP.

Below are two sample INVITE messages that I have tried to send to Messenger 
5.0 without receiving any response (in both cases I had a listener on the 
appropriate UDP ports waiting to intercept any incoming communication so 
that I could analyze it).

Thanks,
Zack
******** Attempt to INVITE 5.0 as Proxy ********
INVITE sip:192.168.111.4:16363;transport=udp SIP/2.0
Via: SIP/2.0/UDP 192.168.111.15:4000
Max-Forwards: 70
From: <sip:[EMAIL PROTECTED]>;tag=38728422
To: <sip:[EMAIL PROTECTED]>
Call-ID: [EMAIL PROTECTED]
CSeq: 1 INVITE
Contact: <sip:192.168.111.15:4000>
Content-Type: application/sdp
Content-Length: 109
v=0
o=- 0 0 IN IP4 192.168.111.15
s=session
c=IN IP4 192.168.111.15
t=0 0
m=x-ms-message 5060 sip null
******** Attempt to INVITE 5.0 masquerading as another client ********
INVITE sip:192.168.111.4:16363;transport=udp SIP/2.0
Via: SIP/2.0/UDP 
192.168.111.15:4000;branch=z9hG4bK1ec1dfd346492d7e92923d736744a78,SIP/2.0/UDP 
192.168.111.15:4020
Max-Forwards: 69
From: <sip:[EMAIL PROTECTED]>;tag=98e6fbb8f5254ddba6e5e15fce967f19
To: <sip:[EMAIL PROTECTED]>
Call-ID: [EMAIL PROTECTED]
CSeq: 1 INVITE
Contact: <sip:192.168.111.15:4020>
Content-Type: application/sdp
Record-Route: <sip:192.168.111.15:4000>
Content-Length: 109

v=0
o=- 0 0 IN IP4 192.168.111.15
s=session
c=IN IP4 192.168.111.15
t=0 0
m=x-ms-message 5060 sip null
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