T.120

T.120 is a suite of point-to-multipoint communication protocols for teleconferencing, videoconferencing, and computer-supported collaboration.^[1] It provides for application sharing, online chat, file sharing, and other functions. The protocols are standardised by the ITU Telecommunication Standardization Sector (ITU-T).^[1]

T.120 has been implemented in various real-time collaboration programmes, including WebEx and NetMeeting.^[2][3] IBM Sametime switched from the T.120 protocols to HTTP(S) in version 8.5.^[4]

The prefix T designates the ITU subcommittee that developed the standard, but it is not an abbreviation. The ITU (re)assigns these prefixes to committees incrementally and in alphabetic order.^[5]

The T.123 standard specifies that T.120 protocols use network port 1503 when communicating over TCP/IP.^[5]

Components

Number	Title	Status	Refs
T.120	Data protocols for multimedia conferencing	In force	[6]
T.121	Generic application template	In force	[7]
T.122	Multipoint communication service - Service definition	In force	[8]
T.123	Network-specific data protocol stacks for multimedia conferencing	In force	[9]
T.124	Generic Conference Control	In force	[10]
T.125	Multipoint communication service protocol specification	In force	[11]
T.126	Multipoint still image and annotation protocol	In force	[12]
T.127	Multipoint binary file transfer protocol	In force	[13]
T.128	Multipoint application sharing[a]	In force	[14][15]
T.130	Realtime architecture	?	[15]
T.131	Network specific mappings	?	[15]
T.132	Realtime link management	?	[15]
T.133	Audio visual control services	?	[15]
T.134	Text chat application entity	In force	[16]
T.135	User-to-reservation system transactions within T.120 conferences	In force	[17]
T.136	Remote device control application protocol	Superseded by H.281	[18][19]
T.137	Virtual meeting room management for multimedia conferencing audio-visual control	In force	[20]
T.RES	Reservation services	?	[3][15]
T.TUD	User reservation	?	[3][15]

1. T.128 was previously called T.Share while in draft stage.

See also

• Interactive whiteboard
• Synchronous conferencing
• Videotelephony
• Web conferencing