V.90

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V.90

(protocol)
An ITU-T standard modem serial line protocol allowing download speeds of up to 56 kbps with upload speeds of 33.6 kbps. V.90 modems are designed for connections that are digital at one end and have only one digital-to-analogue conversion.

As of 1998-02-06 the V.90 standard, formerly called V.pcm, has been given final approval by ITU-T. On 1998-10-27 the ITU-T announced that approval of the V.90 standard was completed. Interoperability testing is complete or in progress for several modem manufacturers. The V.90 standard reconciles two competing standards, X2 and K56flex.

The ITU-T has initiated the approval process for a new all-digital version of the protocol, to be known as V.91.

ITU Press Release 98-04. and NP-3.

V.90

An ITU standard (1998) for an analog modem that communicates at 56 Kbps downstream and 33.6 Kbps upstream. It was designed for ISPs and online services that are digitally attached to the telephone system via T1 and T3 circuits.

In practice, the downstream link is not faster than 45 Kbps in these PCM modems, so called because they use pulse code modulation downstream and standard V.34 upstream. Initially, two incompatible technologies competed in this arena: x2 from U.S. Robotics and K56Flex from Rockwell and Lucent. Such modems can be upgraded to V.90 if they contain software-upgradable memory chips. See V.92, V.34 and channel bonding.
References in periodicals archive ?
We designed the SupraExpress 56e modem to give Mac users easy, online access to the latest innovations in high-speed K56flex technology, which we believe is the emerging defacto 56,000 bps modem standard supported by most major industry players," said Jim Cady, vice president and general manager for Diamond Multimedia's Communications Division.
Diamond Multimedia is a charter member of the Open 56K Forum, an industry-wide coalition founded by twenty-seven leaders from key segments of the communications and computer industries, and dedicated to achieving widespread implementation of 56,000 bps modem technology.
We designed the SupraExpress 56 modem to give users easy, online access to the latest innovations in high-speed K56flex technology, which we believe is the emerging defacto 56,000 bps modem standard supported by most major industry players," said Jim Cady, vice president and general manager for Diamond Multimedia's Communications Division.