Dialogic 6.2 manual Understanding H.323 Functionality, November 226

Managing Calls Using IP Telephony

Understanding H.323 Functionality

	This Brooktrout SDK supports the H.323 protocol (version 4 and
	Annex D), providing end point functionality only. Our current H.323
	implementation does not operate as a gateway or H.323 Gatekeeper,
	but you can configure your application to communicate with a
	gateway or H.323 Gatekeeper.
	The H.323 implementation supports both a primary and alternate
	H.323 Gatekeeper. When an application is configured to
	communicate with a Gatekeeper, all the RAS messages exchanged
	with the Gatekeeper are done inside of the H.323 implementation
	without requiring the application to get involved. The H.323
	implementation registers the end points transport address and alias
	information with the Gatekeeper and resolves destination alias
	addresses with the Gatekeeper. If the application turns on alternate
	Gatekeeper support and the primary Gatekeeper becomes
	unavailable, the H.323 implementation automatically falls back to
	an alternate Gatekeeper without involving the application.
Multiple Protocols	SIP and H.323 can co-exist in the same system. You can configure a
	single hardware module or SR140 module to support either SIP or
	H.323, selecting which protocol stack to use on a per-module basis.
	The protocols can operate simultaneously on different modules.
	Different modules in the same system can support different IP call
	control stacks, but the SR140 Fax Software implementation only
	supports one IP stack at a time.
Supporting Media	The H.323 implementation supports T.38 (Fax Media) and RTP
	media over UDP (H.323 Annex D).
	The H.323 implementation supports the ability to negotiate a pseudo
	G.711 media session with the intent of renegotiating to a T.38 media
	session even when RTP prompt playback/record capability is not
	desired.
	This functionality is required to interoperate with certain supported
	equipment. Media renegotiation to T.38 is also supported after a call
	is setup.
	The H.323 implementation supports basic call control functionality,
	specifically outbound call setup and teardown and inbound call
	detection, answering, and teardown. See the sections on Outgoing IP
	Calls on page 217 and Incoming IP Calls on page 218 for information
	about the functions that support these activities.

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