Glossary-6
ITU-T V.22
The V.22 protocol is used for 1200 bps and
600 bps full-duplex connections. The version
of V.22 your modem supports is Alternative B.
ITU-T V.22bis
The V.22bis protocol enhances V.22 by
adding 2400 bps full-duplex connections.
ITU-T V.23
The modem supports two V.23 modes: one-
way forward channel at 1200 bps with a 75 bps
back channel; and main channel half duplex at
1200 bps. V.23 mode is not supported for
synchronous connections; V.54 digital and
analog loopbacks; leased-line operation; or
MNP and LAPM connections.
ITU-T V.32
The ITU-T V.32 protocol is for full-duplex
data transfer over general switched telephone
networks at 9600 and 4800 bps. V.32 employs
echo cancellation and trellis coded modulation.
ITU-T V.32bis
An MNP or LAPM error-free asynchronous
connection at 14400, 12000, 9600, 7200, or
4800 bps with another modem that supports
MNP or LAPM. The ITU-T V.32bis
specification enhances V.32 by adding 14400,
12000, and 7200 bps speeds and special rate
sequences to shorten speed upshifting and
downshifting.
ITU-T V.34
An MNP or LAPM error-free asynchronous
connection at 28800, 26400, 24000, 21600,
19200, 16800, 14400, or 33600 bps with
another modem that supports MNP or LAPM.
The V.34 protocol being adopted by the ITU-T
provides several modulation enhancements to
make the most of the new, more capable
telephone networks. It operates better over
noisy lines and holds connections more
consistently. V.34 offers full-duplex data
transfer over general switched telephone
networks at several speeds ranging from 14400
bps to 28800 bps, depending on line conditions
encountered during the connection.
Term
Definition
