Glossary (H)
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H.223
Specifies a packet-oriented multiplexing protocol for low bit rate multimedia communications; Annex A & B handles light and medium error prone channels of the mobile extension used in
3G-324M.
H.225.0
H.225.0 specifies the procedures and messages applicable to Gatekeepers, including the RAS protocol for Registration, Admission and Status.
H.235 SECURITY
H.235 security ensures the authentication of each endpoint and the integrity of messages. The basis of the security process is the shared secret between the endpoint and the Gatekeeper.
H.239
Recommendation for role management and additional media channels for H.3xx-series terminals. Sets forth a way to have multiple video channels (e.g., one for conferencing, another for presentation) within a single session (call).
H.245
The ITU-T standard used for the Control Protocol for Multimedia Communication. H.245 is included in the H.225.0 Recommendation. H.245 provides signaling for the proper operation of the H.323 terminal, including capabilities exchange, opening and closing
of logical channels together with a full description of these channels, mode preference requests, flow control messages, and general commands and indications.
H.245 PROXY
The H.245 Proxy enables routing H.245 channels in a point-to- point H.323 call. The H.245 Proxy is a natural extension of a Gatekeeper.
H.245 TUNNELING
H.245 tunneling decreases the time between the point at which an endpoint initiates a call and the point at which the call participants are ready to open multimedia channels. The endpoint must also support H.245 tunneling.
H.248
The ITU-T standard for signaling and control between circuit- switched PSTNs and VoIP networks.
H.249
The ITU-T standard enabling the creation of simple interactive user interfaces for devices equipped with advanced keypads and touch pad inputs. Using this standard, the user experience of handsets and terminals connecting to media servers can be greatly enhanced.
H.261
An ITU-T standard for compressing an H.320 video conferencing transmission. H.261 supports CIF and QCIF resolutions.
H.263
An ITU-T standard video codec. This codec is an enhancement to the H.261 codec. H.263 offers improved compression over H.261 and includes a set of tools aimed at optimizing codec performance.
H.264
MPEG-4 Part 10, or Advanced Video Coding, is a digital video codec standard which is noted for achieving very high data compression. Technically identical to the ISO/IEC MPEG-4 Part
10 standard (formally, ISO/IEC 14496-10).
H.281
The ITU-T standard recommendation for local and far-end camera control protocol for ISDN (H.320) video conferencing.
H.282
The ITU-T standard recommendation that defines a set of services and a protocol which may be used to perform remote device control in a multimedia conference.
H.320
The ITU-T standard for video conferencing over digital networks such as ISDN.
H.323
The ITU-T standard for video conferencing over packet-switched networks such as LANs and the Internet.
H.323 FAST START
See Fast Connect
H.324
The ITU-T standard for video conferencing over analog telephone lines (POTS) using modems.
H.324/M
The Third Generation Partnership Project (3GPP) has adopted the ITU-T Recommendation H.324 Annex C, also referred to as H.324/M (Mobile) or H.324M (with very few changes), on their
3G-324M as the standard for multimedia telephony over 3G circuit switched cellular networks.
H.450
See Supplementary Services
H.460
Standard that promises to make NAT-firewall traversal between vendors’ video conferencing equipment and different end-user organizations much easier.
HANDOVER
The process in which the radio access network changes the radio transmitters or radio access mode or radio system used to provide the bearer services, while maintaining a defined bearer service QoS.
HARD HANDOVER
A category of handover procedures where all the old radio links in the UE are abandoned before the new radio links are established.
HD (HIGH DEFINITION)
A video system of higher resolution than standard-definition (SD), e.g. NTSC, SECAM and PAL.
HSDPA (HIGH-SPEED DOWNLINK PACKET ACCESS)
A mobile telephony protocol. Sometimes referred to as a 3.5G (or "31/2.G") technology. HSDPA provides a smooth evolutionary path for Universal Mobile Telecommunications System (UMTS) networks allowing for higher data capacity (up to 14.4 Mbit/s in the downlink) used for downlink communication to mobile devices.
HSUPA (HIGH-SPEED UPLINK PACKET ACCESS)
A data access protocol for mobile phone networks with extremely high upload speeds up to 5.76 Mbps. Similar to HSDPA (High- Speed Downlink Packet Access), HSUPA is considered 3.75G.