H.323 is a standard for communication protocols from the International Telecommunications Union Telecommunication Standardization Sector (ITU-T); Version 4 is the current version. H.323 was created to provide multimedia communication across a packet network. The protocol can handle video and data, in addition to audio. H.323 interoperates well with the public switched telephone network (PSTN) in translating between call setup and control signals used in an IP network and those used in a switched-circuit network. H.323 is widely used in video conferencing deployments.

Gateways that use H.323 do not depend on a call agent, as with Media Gateway Control Protocol (MGCP). H.323 is the default gateway protocol on Cisco routers. This chapter focuses on Cisco IOS H.323 gateways, although the concepts apply to all H.323 gateways.

In this chapter you will learn

  • H.323 specifications
  • H.323 network components
  • Call flow with H.323 gateways
  • H.323 protocol pros and cons
  • Dial plan considerations
  • Implementing H.323 gateways
  • Securing H.323 gateways
  • Troubleshooting tools

Part I: Voice Gateways and Gatekeepers

Gateways and Gatekeepers

Part II: Gateways

Media Gateway Control Protocol


Session Initiation Protocol

Circuit Options

Connecting to the PSTN

Connecting to PBXs

Connecting to an IP WAN

Dial Plans

Digit Manipulation

Influencing Path Selection

Configuring Class of Restrictions

SRST and MGCP Gateway Fallback

DSP Resources

Using Tcl Scripts and VoiceXML

Part III: Gatekeepers

Deploying Gatekeepers

Gatekeeper Configuration

Part IV: IP-to-IP Gateways

Cisco Multiservice IP-to-IP Gateway

Appendix A. Answers to Chapter-Ending Review Questions


Cisco Voice Gateways and Gatekeepers
Cisco Voice Gateways and Gatekeepers
ISBN: 158705258X
EAN: 2147483647
Year: 2004
Pages: 218

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