What you need to understand is that free/busy in Exchange 2003 is handled by the Schedule+Freebusy folder which is a system folder in the public folder tree. You need to create public folders for the Exchange 2007 server and then replicate the schedule+ freebusy folder from the exchange 2003 public folders to the exchange 2007 public folders. Exchange 2003 cannot read the free/busy info from the CAS. It has to get it from the public folders.
Here is the latest on this issue:
We could not get communication between the configurations I outlined. What I did next was try a program from Quest called Collaboration Services for Exchange. This works on a seperate server that acts as a middle man bwtween the 2 different versions. After 1 day of tweaking we have communication between the 2 seperate versions of Exchange. Unbelievable! A couple months of trying to make it work with IOR or MIIS or whatever solution MS provided and low and behold an app under $3000 provided the solution.
I would recommend Quest software for this – under $3000 for 200 users – and it comes with a very straightforward GUI.
Thnxs to anyone who assisted!