A Word about Exchange Server v5.5
In order to install and manage Unity, you must know a moderate amount about
how to manage and troubleshoot Exchange Server v5.5, as well as how to have
Exchange patched to Service Pack 3. Exchange uses standard directory services,
while Unity uses these directory services for its own user directory.The Unity
administrator will need full administrative access to Exchange in order to administer
the full Unity system.
In large organizations, Exchange designers often use a design that has field
mail servers connecting to, and delivering mail to, one central server, called the
bridgehead server. All Exchange servers receive and deliver mail through this
bridgehead, and user accounts are controlled via this bridgehead.The actual user
mailboxes normally reside at the field server level.This is where Unity functions,
not at the bridgehead.You should ensure each Unity user has a working Exchange
mailbox at the field level, which is where the IP phones reside as well.This is also
true for IP SoftPhone users since all resources must be locally attached.