Glossary
V.22
An ITU-Tstandard for modem communications at 1200 bps, compatible with the Bell 212A standard observed in the U.S. and Canada.
V.22 bis
An ITU-Tstandard for modem communications at 2400 bps.
The standard includes an automatic link negotiation fallback to 1200 bps and compatibility with Bell 212A/V.22 modems.
V.23
An ITU-Tstandard for modem communication at 1200 bps with a 75 bps back channel. This standard is used in the U.K.
V.27ter
An ITU-Tstandard for facsimile operations that specifies modulation at 4800 bps, with fallback to 2400 bps.
V.29
An ITU-Tstandard for facsimile operations that specifies modulation at 9600 bps, with fallback to 7200 bps.
V.32
An ITU-Tstandard for modem communications at 9600 bps and 4800 bps. V.32 modems fall back to 4800 bps when line quality is impaired.
V.32 bis
An ITU-Tstandard that extends the V.32 connection range: 4800, 7200, 9600, 12000, and 14400 bps. V.32 bis modems fall back to the next lower speed when line quality is impaired, fall back further as necessary, and also fall forward (switch back up) when line conditions improve.
See online fall back/fall forward
V.34
An ITU-Tstandard that currently allows data rates as high as 28,800bps.
V.34+
This is an enhancement to V.34 that enables data transfer rates as high as 33,600 bps.