T.120 is an ITU-T recommendation that describes a series of communication and application protocols and services that provide support for real-time, multipoint data communications. It is used by products such as Cisco WebEx's MeetingCenter, Microsoft NetMeeting, Nortel CS 2100 and Lotus Sametime to support application sharing, real-time text conferencing and other functions.
The set of "T.120" recommendations includes:
- T.120 - Data protocols for multimedia conferencing
- T.Imp120 - Revised Implementor's Guide for the ITU-T T.120 Recommendation series
- T.121 - Generic application template
- T.122 - Multipoint communication service - Service definition
- T.123 - Network-specific data protocol stacks for multimedia conferencing
- T.124 - Generic Conference Control
- T.125 - Multipoint communication service protocol specification
- T.126 - Multipoint still image and annotation protocol
- T.127 - Multipoint binary file transfer protocol
- T.128 - Multipoint application sharing (was known as T.share while in draft stage)
- T.134 - Text chat application entity
- T.135 - User-to-reservation system transactions within T.120 conferences
- T.136 - Remote device control application protocol
- T.137 - Virtual meeting room management - services and protocol
The PCMag encyclopedia of computer terms lists the following additional recommendations:
- T.130 - Realtime Architecture - Interaction between T.120 and H.320.
- T.131 - Network Specific Mappings - Transport of realtime data used with T.120 over LANs.
- T.132 - Realtime Link Management - Creation and routing of realtime data streams.
- T.133 - Audio Visual Control Services - Controls for realtime data streams.
- T.RES - Reservation Services - Interaction between devices and reservation systems
- T.Share - this is now known as T.128
- T.TUD - User Reservation - Transporting user-defined data
These are not listed on the official ITU-T website. It is possible that these recommendations have been withdrawn.
T.RES and T.TUD are possibly recommendations that did not make it out of draft stage; the ITU practice is to use the series letter + an alphanumeric code for the recommendation while it is in draft, and a number after publication.