Bell 212A

The Bell 212A modulation scheme defined a standard method of transmitting full-duplex asynchronous serial data at 1.2 kbit/s over analogue transmission lines. The equivalent, but incompatible ITU-T standard is V.22.

Device

The Bell 212 Dataset is a 1979-vintage modem used for communicating over telephone lines at 300 or 1200 bits per second.[1] The 212A standard provides for the ability of a modem to auto-answer a ringing phone.[2]

Usage

The Bell 212A scheme was the most common standard used for 1200 bps transmission on US data networks such as CompuServe during the period that dial-up Internet access was the norm (1980s and 1990s).[3][2]

See also

References
  1. "BSP 592-039-100: Data Set 212AR-L1A/2A -- Transmitter-Receiver -- Description and Operation", Bell System Practices, American Telephone & Telegraph Co, June 1979
  2. Frank J. Derfler, "The Universal Data Systems' 212 LP modem", InfoWorld, pp. 52-53, 9 August 1982.
  3. Frank J. Derfler Jr., "Selecting the right modem", PC Magazine, pp. 224-233, January 1983.


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