Gateways and Gatekeepers


	Gateways, Gatekeepers and H.323 - Technology Overview H.323 Architecture comprises of four logical components: • Terminals are H.323 devices that can support Audio, Video and Data calls in any combination. • Gateways allow calls to be made to non-H.323 devices, for instance an analog telephone or the public network. • Multipoint Connection Units (MCU) facilitate multipoint conferences • Gatekeepers control the call processing for all of the above. These four devices types are grouped together in what is known as an H.323 zone (a zone is analogous to a PABX). Each zone has a single Gatekeeper that can be considered as the brains of the system dealing with call distribution; call control and the management of resources. Upon starting, terminals, Gateways and MCUs make a registration request against a Gatekeeper who authenticates, accepts or rejects their request to become a member of the zone. Once accepted, a terminal wishing to make a call sends a call set-up message to the Gatekeeper who will then send an alert to the called party or if the call is to a non-H.323 terminal establish the call via a Gateway. The design of IP Telephony systems has been driven with open standards in mind. IP Phones, Gateways & Gatekeepers all support the H.323 standard and it is this that allows devices from different manufacturers to work together. IP Office has the integral Gateway and Gatekeeper functionality required to provide a fully functional IP Telephony environment. Telephone Systems Avaya IP Office Partner Telephone Systems Avaya VoIP telephones Gateways, Gatekeepers and H.323 - Technology Overview

Gateways, Gatekeepers and H.323 - Technology Overview

H.323 Architecture comprises of four logical components:

• Terminals are H.323 devices that can support Audio, Video and Data calls in any combination.

• Gateways allow calls to be made to non-H.323 devices, for instance an analog telephone or the public network.

• Multipoint Connection Units (MCU) facilitate multipoint conferences

• Gatekeepers control the call processing for all of the above. These four devices types are grouped together in what is known as an H.323 zone (a zone is analogous to a PABX). Each zone has a single Gatekeeper that can be considered as the brains of the system dealing with call distribution; call control and the management of resources. Upon starting, terminals, Gateways and MCUs make a registration request against a Gatekeeper who authenticates, accepts or rejects their request to become a member of the zone. Once accepted, a terminal wishing to make a call sends a call set-up message to the Gatekeeper who will then send an alert to the called party or if the call is to a non-H.323 terminal establish the call via a Gateway.

The design of IP Telephony systems has been driven with open standards in mind. IP Phones, Gateways & Gatekeepers all support the H.323 standard and it is this that allows devices from different manufacturers to work together. IP Office has the integral Gateway and Gatekeeper functionality required to provide a fully functional IP Telephony environment.

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Avaya IP Office
Partner Telephone Systems
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