V.42

The ITU-T V-Series Recommendations on Data communication over the telephone network specify the protocols that govern approved modem communication standards and interfaces.

Note: the and suffixes are ITU-T standard designators of successive iterations of a standard (bis and ter are derived from the Latin for "twice" and "thrice").

Applies to V.1–V.9

Applies to V.10–V.34

In order to gain first-mover advantage, many modem companies introduced models based on upcoming V-series standards before they reached final ratification. In other cases, companies introduced non-standard systems but gave them ITU-like names.

Applies to V.35–V.39

Applies to V.40–V.49

Applies to V.60–V.99

Applies to V.100–V.199

Applies to V.200–V.249

Applies to V.250–V.299

Applies to V.400–V.499

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