T.120
# T.120

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

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

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.

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

## Components

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| T.136 | Remote device control application protocol | Superseded by H.281 |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

* ↑ T.128 was previously called T.Share while in draft stage.
