Regenerate Address Book – OCS vs Lync 2010 vs Lync 2013

Updating the address book in OCS and Lync requires regeneration of the address book server-side, but also requires forcing the client to download the newly-generated version.
There are 3 steps from AD changes to the client address book. These are:

  1. Changes in AD are replicated into the rtcab database by the LS user replicator every minute
  2. Every 24 hours (by default at 01:30) the address book server service will pull the changes from the rtc database into the address book files.
  3. At a random time the client will download a new address book file (or delta files as appropriate) to update the GalContacts.db

This can lead to some considerable delays in changes appearing in the client address book, which you may want to reduce.


OCS: Forcing a regeneration of the address book in OCS 2007 R2 requires the use of  abserver.exe. This address book server service creates new address book files  and sets of delta files for use by the address book download service for different clients. To force an immediate resynchronisation, run abserver.exe -SyncNow. SyncNow is the equivalent of step 2 above.  Step 1 can also be forced by use of the -regenUR switch, which regenerates all data in the database from AD.  More information on abserver can be found here

Lync: Lync now uses powershell to replace the various exe’s, vbs’s and so on used in OCS. Update-csAddressBook is used to force step 2. Additional configuration can be viewed by using get-csAddressBookConfiguration as shown below.

Again, if step 1 is required run Update-csUserDatabase to regenerate the database from AD.


To force the client to download a new copy of the address book at login to Lync2010/OCS create a new DWORD registry key under:


For Lync 2013 this is now located under:


named GalDownloadInitialDelay with a value of zero.

Delete the GalContacts.db and GalContacts.db.idx from the users profile:
In Windows XP: %userprofile%\Local Settings\Application Data\Microsoft\Communicator\sip_<username@domain>\

In Windows Vista or Windows 7:


For the Lync 2013 client this is now:


Restart the Communicator or Lync client.

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