You update one of the telephone numbers of a Microsoft Office Communicator 2007 R2 user (User A) in the Active Directory directory service. User A has multiple telephone numbers. However, after some time, the telephone numbers of User A that are not updated are missing in the Office Communicator 2007 R2 client of User B.
This issue occurs because of a defect in the code that merges the compact delta file and the full offline address book (GalContacts.db) file. Therefore, only updated telephone numbers are copied, and existing telephone numbers are removed in the new GalContacts.db file.
To fix this problem, install the following cumulative update:
2291453 Description of the cumulative update package for Communicator 2007 R2: November 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.