Registering asterisk with Microsoft OCS as sip client

Trying to register asterisk with MS OCS as a sip client. I’m not getting a response. I think this is due in part to OCS wanting an initial REGISTER with no credentials so it can do an NTLM challenge?

Anyway, this is what is in my sip.conf:

The following is the REGISTER message being sent. I’ve replaced the IPs in the SIP header.
sip.example.com == 192.168.0.1
my asterisk server == 192.168.0.2

REGISTER 10 headers, 0 lines Reliably Transmitting (no NAT) to 192.168.0.1:5061: REGISTER sip:example.com SIP/2.0 Via: SIP/2.0/TLS 192.168.0.2:5061;branch=z9hG4bK0c1fbb6d Max-Forwards: 70 From: <sip:first.m.last@example.com>;tag=as3d8b8c33 To: <sip:first.m.last@example.com> Call-ID: 7f26d5ce62a8745716a9ed2a62917fd2@192.168.0.2 CSeq: 104 REGISTER User-Agent: Asterisk PBX 1.8.3.2-1digium1~lucid Expires: 120 Contact: <sip:from-ocs@192.168.0.2:5061;transport=TLS> Content-Length: 0

And finally, the error message itself.

[Apr 14 16:48:05] NOTICE[16267]: chan_sip.c:12232 sip_reg_timeout: -- Registration for 'first.m.last@sip.example.com' timed out, trying again (Attempt #3) Really destroying SIP dialog '7f26d5ce62a8745716a9ed2a62917fd2@192.168.0.2' Method: REGISTER

Microsoft’s OCS / LCS / Lync implementation is not compliant with the SIP RFC. Any successful connection between the two will be a hack.

Google turns up a few threads specific to this topic.

Good luck!