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56 kbps

56 kbps (56 kilobits per second, correctly 56 kbit/s) is the data capacity of a normal single channel digital telephone line in North America. The figure is derived from the bandwidth of 4 kHz allocated for such a channel and the 16-bit encoding (4000 times 16 = 64000) used to change analogue signals to digital, minus the 8000 bit/s used for signalling and supervision.

At the end of 1997 there were two rival modem designs capable of this rate: k56flex and US Robotics' X2. In February 1998 the ITU proposed a 56 kbit/s standard called V.90, which is expected to be formally approved during September 1998.

This article (or an earlier version of it) contains material from FOLDOC, used with permission. Update as needed.