The standards that are relevant to contemporary videoconferencing are:

• H.320 for circuit-based networks, such as ISDN, and
• H.323 for packet-based networks, such as the Internet.

Both of these standards are International Telecommunications Union (ITU)

Recommendations (the formal name the ITU uses for its standards). They can be found at: http://www.itu.int/rec/recommendation.asp?type=products&parent=TRECh/

These standards define, in detail, the processes and procedures used for standards-based videoconferencing, over ISDN and Internet Protocol (IP) networks (such as the Internet itself).

Equipment needs to support these standards in order to interoperate with other videoconferencing equipment made and used in different countries, and/or developed by different manufacturers. This does not preclude a particular manufacturer's equipment from having a proprietary means of communicating, as long as it can also use the defined standards when interoperating with equipment that does not support those proprietary standards.

For some time JANET has supported videoconferencing using commercial ISDN services offered by telecommunications companies and Janet Videoconferencing.

At the time of writing, a videoconferencing service that will make use of the JANET IP data network is being piloted. Only equipment that supports the relevant standards will be supported by either of these services.

The standards that have been produced to define videoconferencing have included a data sharing element, and this is also defined in an ITU recommendation: T.120 "Data protocols for multimedia conferencing": http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=TRECt.120

This means that the same data sharing protocol applies to both the IP/H.323 and the ISDN/H.320 domains. It should be noted that T.120 data sharing (like video) is an optional feature of an H.323 terminal.

The T.120 standard supports a number of data sharing features including whiteboards, textual chat, application sharing, interactive data sharing and desktop sharing.