Sets of telecommunications protocols and interfaces defined by CCITT (now ITU-T ) Recommendations. Note: Some of the more common V.-series Recommendations are:
V.21: A CCITT Recommendation for modem communications over standard commercially available lines at 300 b/s. This protocol is generally not used in the United States.
V.22bis: A CCITT Recommendation for modem communications over standard commercially available voice-grade channels at 2,400 b/s and below.
V.32: A CCITT Recommendation for modem communications over standard commercially available voice-grade channels at 9.6 kb/s and below.
V.32bis: A CCITT Recommendation for modem communication over standard commercially available voice-grade channels at 14.4 kb/s and below.
V.34: An ITU-T Recommendation for modem communication over standard commercially available voice-grade channels at 28.8 kb/s and below.
V.42: A CCITT Recommendation for error correction on modem communications .
V.42bis: A CCITT Recommendation for data compression on a modem circuit .
V.FAST: A new CCITT Recommendation for high-speed modems currently under development.