When I logged into CWA and displayed the contact card for one of my test users, he doesn't have a phone number. Another test user does have a number, and from what I can tell, both users are configured identically. I checked in a MOC client, and got the same result. Where does OCS store these numbers, or where does it pull it from? This issue isn't critical, of course, it's just more out of curiosity.
Basically the numbers are pulled from mulitple Active Directory attributes (telephoneNumber, otherPhone, etc) and inserted in the OCS SQL database, then put into the server's Address Book files. The Communicator client picks up the changes during sign-in. Also, if numbers in AD are not normalized correctly into E.164 format they will not display in the client.