Cisco 3725 Software Configuration Guide - Page 127

CHAPTER 4 Configuring Voice-over-IP This chapter explains how to configure voice network modules with receive and transmit (E&M), Foreign Exchange Office (FXO), and Foreign Exchange Station (FXS) interfaces for your router. Voice network modules convert telephone voice signals into a form that can be transmitted over an IP network. This chapter is divided into the following sections: • Voice-over-IP Prerequisites, page 4-1 • Configuring the Voice Interface, page 4-2 • Voice-over-IP Configuration Examples, page 4-3 • Where to Go Next, page 4-11 You need both a voice network module and a voice interface card for a voice connection. You can install one voice interface card in a 2-channel voice network module, and two voice interface cards in a 4-channel module. At least one other network module or WAN interface card must be installed in the router to provide the connection to the IP LAN or WAN. Voice over IP (VoIP) enables your router to carry live voice traffic (for example, telephone calls and faxes) over an IP network. VoIP offers the following benefits: • Toll bypass • Remote PBX presence over WANs • Unified voice/data trunking • Plain old telephone service (POTS)-Internet telephony gateways Voice-over-IP Prerequisites Before you can configure your router to use VoIP, you must first do the following: • Establish a working IP network. For more information about configuring IP, refer to the "Configuring IP" chapter in the Cisco IOS Release 11.3 Release Network Protocols Configuration Guide, Part 1. • Install the voice network module into your router. For more informationabout the voice network modules, refer to the "Connecting Voice Network Modules to a Network" chapter in the Cisco Network Modules Hardware Installation Guide. • Complete your company's dial plan. That is, decide what patterns of dialed numbers will access what telephony endpoints. • Establish a working telephony network based on your company's dial plan. • Integrate your dial plan and telephony network into your existing IP network topology. OL-1957-04 Software Configuration Guide for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Routers 4-1