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H.323
From Wikipedia,
the free encyclopedia
H.323 is an umbrella recommendation
from the ITU Telecommunication Standardization Sector (ITU-T)
that defines the protocols to provide audio-visual communication
sessions on any packet network. It is widely implemented by voice
and videoconferencing equipment manufacturers, is used within
various Internet real-time applications such as NetMeeting and
Ekiga, and is widely deployed worldwide by service providers
and enterprises for both voice and video services over Internet
Protocol (IP) networks. It is a part of the ITU-T H.32x series
of protocols, which also address multimedia communications over
Integrated Services Digital Network (ISDN), Public switched telephone
network (PSTN) or Signaling System 7 (SS7), and 3G mobile networks.
History
The first version of H.323 was published by
the ITU in November 1996 with an emphasis of enabling videoconferencing
capabilities over a Local Area Network (LAN), but was quickly
adopted by the industry as a means of transmitting voice communication
over IP networks (see VoIP).
One strength of H.323 was the relatively early
availability of a set of standards, not only defining the basic
call model, but also the supplementary services needed to address
business communication expectations. H.323 was the first VoIP
standard to adopt the Internet Engineering Task Force (IETF)
standard Real-time Transport Protocol (RTP) to transport audio
and video over IP networks.
H.323 call signaling is based on the ITU-T
Recommendation Q.931 protocol and is suited for transmitting
calls across networks using a mixture of IP, PSTN, ISDN, and
QSIG over ISDN. A call model, similar to the ISDN call model,
eases the introduction of IP telephony into existing networks
of ISDN-based PBX systems, including transitions to IP-based
Private Branch eXchanges (PBXs).
Within the context of H.323, an IP-based PBX
might be an H.323 Gatekeeper or other call control element that
provides service to telephones or videophones. Such a device
may provide or facilitate both basic services and supplementary
services, such as call transfer, park, pick-up, and hold.
Over the years, H.323
has been revised and re-published with enhancements necessary
to better-enable both
voice and video functionality over packet-switched networks,
with each version being backward-compatible with the previous
version. Recognizing that H.323 was being used for communication,
not only on LANs, but over WANs and within large carrier networks,
the title of H.323 was changed when published in 1998. The title,
which has since remained unchanged, is "Packet-Based Multimedia
Communications Systems." The current version of H.323, commonly
referred to as "H.323v6", was published in 2006. [Continue
Reading and Links At]:
Source: http://en.wikipedia.org/wiki/H.323
OpenH323 Project
The OpenH323 project aims to create a full featured,
interoperable, Open Source implementation of the ITU-T H.323
teleconferencing protocol that can be used by personal developers
and commercial users without charge.
OpenH323 development is coordinated by Quicknet Technologies
Inc. but is open to any interested party. Commercial and private
use of the OpenH323 code, including use in commercial products
and resale, is encouraged through use of the MPL (Mozilla Public
license).
Home: http://www.openh323.org/
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