Cisco Systems ATA 188 manual Terminals, Gateways

Chapter 1 Cisco Analog Telephone Adaptor Overview

H.323 Overview

Components that the H.323 standard employs include a system of interconnected voice terminals, gateways, gatekeepers, multipoint control units (MCUs), and proxy servers. Voice terminals provide point-to-point and point-to-multipoint conference capability for audio, video, and data. Voice gateways interconnect the packetized IP network to the PSTN or ISDN network. Gatekeepers provide admission control and address translation services for H.323 voice terminals and gateways. MCUs enable two or more gateways to engage in point-to-point or point-to-multipoint audio or video conferences.

This section contains descriptions of the following H.323 components:
• H.323 Terminals, page 1-3
• H.323 Gateways, page 1-3
• H.323	Gatekeepers, page 1-4
• H.323	MCUs, page 1-4
• H.323	Proxy Server, page 1-4
Figure 1-4	H.323 Architecture
		Multipoint Control
H.323 Gatekeeper		Unit (MCU)	Analog Phone

	H.323 Gateway
H.323	CSN/PSTN
Network

Terminal

72858

Analog Phone

Terminal Cisco ATA

H.323 Terminals

Voice terminals in an H.323 network must feature system control units, media transmission capabilities, audio codecs, and network interfaces suitable for transmitting and receiving packetized data.

H.323 Gateways

H.323 gateways feature a mixture of characteristics of both standard Switched Circuit Network (SCN) access points and H.323 access points. Gateways perform the translation of audio, video, and data transmission formats as well as interacting with communications systems and various protocols. A primary responsibility of an H.323 gateway is the call setup and teardown necessary to complete a call to and from a packetized IP network and a standard switched network.

Note Gateways are necessary in an H.323 system to connect calls over a packetized IP network to a switched circuit network such as the PSTN.

Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide (H.323)

OL-4008-01 1-3