Connecting to the PSTN

One of the most important functions of the Cisco voice gateway is to provide an interface from a packet voice network to a time-division multiplexing (TDM) network, such as the public switched telephone network (PSTN) or a PBX. This connection enables you to place calls to, or receive calls from, the outside world, and it can also assist in migration from a TDM PBX to a Voice over IP (VoIP) solution. In this chapter, you will learn about the connection methods used between the Cisco voice gateway and the PSTN.

This chapter helps you to do the following:

• Understand the factors that affect circuit selection when connecting to the PSTN
• Understand the benefits and limitations of each of the different types of circuits available
• Understand the information needed from the PSTN to properly configure a PSTN trunk circuit
• Understand how to configure Cisco voice gateways for each circuit type when connecting to the PSTN
• Verify and troubleshoot circuit connections to the PSTN