Dial tone portability in Exchange Server 2010 provides a temporary mailbox for users when their primary mailbox becomes unavailable due to database, server, or site failures. It allows administrators to create an empty dial tone database, restore the failed database, swap the databases, and then merge the databases to provide a single, up-to-date mailbox for each user. There are several steps involved in performing a dial tone recovery to minimize data loss and downtime for users.

1. Dial Tone Recovery

2.  Dial tone portability is a feature of Microsoft
Exchange Server 2010 that provides a solution for
failures that affect a mailbox database, a server, or
an entire site.
 Dial tone portability enables users to have a
temporary mailbox for sending and receiving e-
mail while their original mailbox is being restored
or repaired.
 After the user's original mailbox data has been
restored, an administrator can merge a user's
recovered mailbox and the user's dial tone mailbox
into a single, up-to-date mailbox.

3.  The process for using dial tone portability is called
a dial tone recovery.
 Dial tone database :-allows users to send and receive
e-mail messages while the failed database is
recovered.
 There are three options for performing a dial tone
recovery:-
 Dial tone recovery on the server with the
failed database
 Dial tone recovery using an alternate server
for the dial tone database
 Dial tone recovery using and staying on an
alternate server for the dial tone database

4.  Create an empty dial tone database to replace
the failed database
 Restore the old database
 Swap the dial tone database with the restored
database
 Merge the databases

5.  You must have fewer than the maximum number
of databases deployed to create a dial tone
database.
 Use the Shell to perform a dial tone recovery on a
single server
 Make sure that any existing files for the database
being recovered are preserved in case they're
needed later for further recovery operations.
 Use the New-MailboxDatabase cmdlet to create a
dial tone database, as shown in this example.
 New-MailboxDatabase -Name DTDB1 -
EdbFilePath D:DialToneDTDB1.EDB

6.  Use the Set-Mailbox cmdlet to rehome the user
mailboxes hosted on the database being recovered,
as shown in this example.
Get-Mailbox -Database DB1 | Set-Mailbox -
Database DTDB1
 Use the Mount-Database cmdlet to mount the
database so client computers can access the
database and send and receive messages, as shown
in this example.
Mount-Database -Identity DTDB1
 Create a Recovery Database.
 Mount the RDB, and then use the Dismount-
Database cmdlet to dismount it, as shown in this
example.
 Mount-Database -Identity RDB1 Dismount-
Database -Identity RDB1

7.  After the RDB is dismounted, move the current
database and log files within the RDB folder to
a safe location. This is done in preparation for
swapping the recovered database with the dial
tone database.
 Dismount the dial tone database:-Dismount-
Database -Identity DTDB1
 Move the database and log files from the dial
tone database folder into the RDB folder.
 Move the database and log files from the safe
location containing the recovered database into
the dial tone database folder, and then mount
the database, as shown in this example.
Mount-Database -Identity DTDB1

8.  Mount the RDB, as shown in this example.
Mount-Database -Identity RDB1
 Use the Get-Mailbox and Restore-Mailbox
cmdlets to export the data from the RDB and
import it into the recovered database:-Get-
Mailbox -Database DTDB1 | Restore-Mailbox -
Recovery Database RDB1
 After the restore operation is complete, you can
dismount and remove the RDB, as shown in
this example:-Dismount-Database -Identity
RDB1 Remove-Mailbox Database -Identity
RDB1

9.  PROS
 The amount of data that must be merged is
minimized.
 The final database size will be less than if you
merged the original data.
 The original mailbox rules, forms, and other
ancillary data will be preserved in the state they
were in before the disaster.
 By using the recovery storage group, you can
avoid building an extra server and, if you keep all
databases on the same drive, eliminate the time
needed to copy large files between disks and
servers.

10.  CONS
 The administrator must have cleared all the
Mailbox box prerequisites cleared in order to
proceed.

11.  During the first two steps of Messaging Dial
Tone recovery, the dial tone database
provides service for users while you recover
the damaged database

12.  After you swap the two databases, users gain
access to previous data

13.  Use Mailbox Merge to bring the recovered
mailboxes up-to-date with content that was
created during the restore and recovery
process