ATM does not stand for automatic teller machine. In the telecommunication, it stands for Asynchronous Transfer Mode, in which data sends asynchronously. This mode is another fast packet switching mode.

ATM is regarded as the technology of the 21st century and its impact is expected to be similar to PCM (pulse code modulation) which is used widely around the world in telecommunication.

Asynchronous transfer mode (ATM) is a technology that has his its history in the development of broadband ISDN in the 1970s and 980s. Technically, it can be viewed as an evolution of pocket switching. Like packet switching for data , ATM integrates the multiplexing and switching functions, is well suited for bursty traffic and allows communications between devices that operate at different speeds . Unlike packet switching , ATM is designed for high-performance multimedia networking.

 ATM is also a set of international interface and signaling standards defined by the International Telecommunication Union- Telecommunications (ITU-T) Standards Sector (formerly the CCITT). The ATM forum has played a pivotal role in the ATM market since its formulation in 1991.

The ATM forum is an international voluntary organization composed of vendors , service providers, research organization, and users. Its purpose is to accelerate the use of ATM products and services through the rapid convergence of interoperability specifications, promotion of industry cooperation , and other activities. Developing multivendor implementation agreements also furthers this goal.

What is ATM ?

Asynchronous transfer mode is a high speed; packet based multiplexing technique in which information flow is organized in short fixed length cells.

The cells are generated when there is new data to send, which allows an element of data compression (e.g there is no need to send the pauses that occurs in speech). It also means that cells with different bandwidth in each direction are possible- a fax connection, for example uses little bandwidth in return direction. This allows more efficient use of the network resourses.

ATM provides a way of multiplexing many sources of data onto a common cells stream. Regardless of speed of the inputs. This greatly improves flexibility, enabling provision of bandwidth on demand.