Dial Tone Portability

Microsoft Exchange Server 2007 will reach end of support on April 11, 2017. To stay supported, you will need to upgrade. For more information, see Resources to help you upgrade your Office 2007 servers and clients.


Applies to: Exchange Server 2007, Exchange Server 2007 SP1, Exchange Server 2007 SP2, Exchange Server 2007 SP3

The Microsoft Exchange Server 2007 dial tone recovery feature offers the following:

  • Provides a limited business continuity solution for database, server, and site loss scenarios.

  • Gives users the ability to send and receive e-mail messages, without having access to historical data stored on the server, during the recovery process.

  • Gives the Exchange administrator time to proceed with the recovery process to bring historical mailbox data online, without total loss of e-mail functionality.

  • Provides users with limited access to their e-mail stored in an offline folder file (.ost file).

  • After the recovered database is brought back online, provides the ability to merge the dial tone and recovered databases into a single up-to-date mailbox database.

Exchange 2007 dial tone portability further enhances the dial tone recovery scenario, by allowing a dial tone recovery to take place on any Exchange 2007 mailbox server in the Exchange organization.

How Dial Tone Recovery Works with Dial Tone Portability

The new Exchange dial tone portability feature enhances existing dial tone disaster recovery scenarios for server and site-level disasters by:

  • Streamlining the creation of dial tone mailboxes on alternate servers.

  • Ensuring the users access to the new mailbox, by automatically reconfiguring Microsoft¬†Office Outlook 2007 client profiles.

  • Allowing for the merger of the recovered historical data and the dial tone mailbox data by means of a wizard, or sequence of management shell tasks.

Dial tone portability allows a user's mailbox to be moved without having access to any of the mailbox content. This allows an alternative server to house the mailboxes of users who were previously on a server that is no longer available. With the Outlook 2007 and Exchange 2007 Autodiscover service, clients are redirected to the new server when they try to connect, removing the past requirement that the Outlook profile be modified to redirect a user to a new server. Users are then moved to this new server and quickly regain the ability to send and receive e-mail messages. In this event, another alternative would be for a new mailbox database to be created on an existing mailbox server. Users can then be moved to the existing server.


When you create a dial tone database, you lose not only all messages, but also all rules, forms, views, and other mailbox metadata. For more information about the end-user configuration information that is lost when resetting a database, see Microsoft Knowledge Base article 282496, XADM: Considerations and Best Practices When Resetting an Exchange Mailbox Database. This information is recovered during the merge process if you merge the dial-tone data into the original database.