Gateways

Abstract

Gateways provide a number of methods for connecting an IP telephony network to the Public Switched Telephone Network (PSTN), a legacy PBX, or key systems. Gateways range from specialized, entry-level and stand-alone voice gateways to high-end, feature-rich integrated router and Cisco Catalyst gateways. This chapter explains important factors to consider when selecting a Cisco gateway to provide the appropriate protocol and feature support for your IP Telephony network. The main topics discussed in this chapter include: • Traffic Patterns and Gateway Sizing, page 13-2 • TDM and VoIP Trunking Gateways, page 13-7 • Understanding Cisco Gateways, page 13-8 • Gateway Selection, page 13-9 • Fax and Modem Support, page 13-19 • Gateways for Video Telephony, page 13-27