We have an on-premise Exchange 2010 SP2 server and OCS 2007 R2. I've successfully setup a hybrid connection to Office 365/exchange online and migrated a couple of test users email boxes. Out domain is federated via ADFS to 365. When logging in to their computers, the cloud users are continually prompted for their credentials for OCS/Communicator. Once they enter in their credentials, everything works fine (IM, Presence, Free/Busy, Out of Office ,etc...) but they will still get prompted for their credentials throughout the day. The email part also works fine - they can send/receive email to other cloud users and on-premise users. TestExchangeConnectivity.com passes. Autodiscover points to our on-premise exchange server. A colleague thought it could be a certificate issue but i've been unable to find any expired certs. This is my last hurdle before starting to migrate "real" users and i've spent days trying to figure this out and MS has been little help. I'm really stumped on this one.
Dan Schoeneman