Topic Last Modified: 2011-03-24

Microsoft Lync Server 2010 creates and uses an Address Book Service to supply clients with these features:

The Address Book Service (ABS) along with the Address Book Web Query (ABWQ), service all client types in Lync Server 2010. The ABS further enhances the performance of the infrastructure by contacting Active Directory (AD DS) at scheduled intervals to collect and update information stored in the ABS databases. The databases (Rtcab and Rtcab1) are stored as part of the databases deployed on either an Enterprise or Standard Edition Front End for the operation of the Front End, similar to information managed and maintained for presence information.

The Address Book Service and the Address Book Web Query perform similar functions, but in different ways. The ABS queries and downloads information from AD DS to be maintained in either a full download of contact information, delta files, or compact delta files. By maintaining the three types of download extracts, a new client can receive the full download and then receive either delta files or compact delta files, based on current need of the client.

Distribution List Expansion is a feature inherent to the way that contacts are stored in the ABS database files or the ABWQ. With the ABS files, the contact is associated with the groups and members of the groups. Group information is available to the client through the updated ABS files. ABWQ will directly query AD DS in the event a client asks for group membership of a client and return the group membership after the information is retrieved from AD DS.

For a fully functional communications system involving telephony, normalizing phone numbers into a usable format – regardless of where the client is – is a critical feature. If a user is making a voice call to another person on a public switched telephone network (PSTN), the phone number of the other person may be in a format that may not work without being reformatted to conventions that are accepted on the PSTN. For example, the user calls the other contact at the number that is listed for them. The number listed for the contact is from AD DS, which does not perform any phone number normalization. The number might be in the form of 555-1010. Phone number normalization will convert the local form 555-1010 to +14255551010. Normalization occurs when ABS reads the information from AD DS and normalizes it, then stores the normalized form in the address book file and index databases – RTCab and RTCab1.

What’s New, What’s Changed in Lync Server 2010 Address Book Services

Lync Server 2010 improves on the Address Book Services from previous releases, namely Microsoft Office Communicator 2007 and Microsoft Office Communicator 2007 R2. Changes that have been made include:

Client Usage of the Address Book Web Query

The Address Book Web Query is available to Lync 2010 and Lync 2010 Phone Edition. For backward compatibility, Microsoft Office Communicator and Microsoft Communicator Mobile can use the Address Book Web Query service. However, Lync and Office Communicator will use the Address Book Service if it is available. The following table shows which client will use which service, based on availability.

Address Book Service Availability Communicator 2007, Communicator 2007 R2, or Lync Communicator Phone Edition or Lync Phone Edition Communicator Mobile or Lync Web App

ABS and ABWQ available

Will use the ABS file download

Will use ABWQ

Will use the ABWQ

ABWQ only

Will use ABWQ

Will use ABWQ

Will use ABWQ

ABS only

Will use ABS file download

Will use ABS/Device file download

Will disable contact search

An in-band provisioning setting determines if the Address Book Service is available. The in-band provisioning setting AbsUsage is defined as one of three values:

  • WebSearchOnly

  • FileDownloadOnly

  • WebSearchAndFileDownload

For those clients that prefer the Address Book Service, they will then use the Address Book Service download files over the Address Book Web Query. If the Address Book Service is not available, then the Address Book Web Query is used on a per request basis against the RTCab or RTCab1 database, depending on which one is currently active.

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