I am able to setup the phone as per the provided instructions in CUCM 8.03 and it registers fine.
However I ran into a problem - outgoing calls work but incoming calls to the n900 don't. The phone rings but when you answer it immediately hangs up.
I have tried setting up the phone as basic and as advanced third party sip phone in the call manager and changing the transport to UDP to no avail.
Any help would be appreciated. My e61i and e71 were able to do this just fine so I know it is not the cisco infrastructure - it is a problem with the phone.