Understanding Unified Messaging Server Topologies

Applies to: Exchange Server 2010

Microsoft Exchange Server 2010 supports a server architecture that distributes server tasks among different server roles. In this kind of architecture, a Unified Messaging (UM) server accepts incoming calls. The Unified Messaging server then routes the messages to the appropriate server for processing. This could be the Client Access server, the Mailbox server, or the Hub Transport server. The server that has the Hub Transport server role installed was formerly known as a bridgehead server.

This topic describes the relationship between the Unified Messaging servers on a typical network and the telephony components in an organization.

UM Topology That Has a Single PBX

The following figure illustrates an Exchange Server 2010 Unified Messaging topology that contains a single Private Branch eXchange (PBX).

UM topology that has a single PBX

UM Topology That Has Multiple PBXs

The following figure illustrates an Exchange 2010 Unified Messaging topology that contains multiple PBXs.

UM topology that has multiple PBXs

The following figure illustrates centralized management system for an Exchange 2010 Unified Messaging topology that contains multiple PBXs. This configuration enables the placement of all Unified Messaging servers in a single location. IP gateways are deployed in each branch office, and replace the legacy voice messaging system for each branch office. Because IP gateways are close to the PBX, the Hub Transport, Client Access, and the Mailbox servers can be removed from both the Mexico City and the Austin sites.