Preferably one that can work with Office Communications Server 2007 R2.
Unfortunately, as of the most recent Communicator client for Mac, there isn't true SIP phone/PBX support. I know someone out there has had to tackle this problem before, so I am curious if anyone has some recommendations?
Good question! I haven't been able to find anything yet. How hard could it be for MS to modify Mac Messenger so that you could dial a number. Who cares if I don't have all the Enterprise Voice features that Communicator has because a lot of those can be set via Communicator Web Access. I just want to be able to dial out. I can call someone via a SIP address and answer incoming calls. Even though I can call Exchange UM voicemail via its SIP address I have no way to enter my PIN which isn't voice enabled. Very frustrating when trying to implement in a multi platform environment!
Only thing I've seen so far is using Evangelyze's SmartSIP product with X-Lite on the Mac. It sure isn't pretty and there is no integration with Entourage or Messenger, but it works.
I'm bummed Microsoft has neglected incorporating this into Messenger. Seems like they alternate what they focus on during releases. 7 was an upgrade to includes OCS support, and 8 is finally adding A/V to the MSN side. Maybe version 9 in another 2 years will actually support VoIP.