Chapter 3. Overview of PSTN and Intersite Connectivity Options

Cisco Unified Communications Manager (CUCM) multisite deployments can use a vast range of connection options to the public switched telephone network (PSTN) and various wide-area network (WAN) technologies for connections between sites. At the turn of the century, the majority of U.S.-based companies were using primary rate interface (PRI ISDN) circuits and some flavor or WAN technologies such as Frame Relay, Asynchronous Transfer Mode (ATM), T1, and so on.

Fast forward just a few short years and Session Initiation Protocol (SIP) adoption has grown multifold, so have alternative WAN technologies that offer high-speed WAN connections between sites. With the increase in WAN speed, many ...

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