3Com 56k User's Manual And Reference page 45

V.17
An ITU-T standard for making facsimile
connections at 14,400 bps, 12,000 bps, 9600 bps,
and 7200 bps.
V.21
An ITU-T standard for modems operating in
asynchronous mode at speeds up to 300 bps, full-
duplex, on public-switched telephone networks.
V.22
An ITU-T standard for modem communications at
1200 bps, compatible with the Bell 212A standard
observed in the U.S. and Canada.
V.22 bis
An ITU-T standard 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.
Glossary
V.23
An ITU-T standard for modem communication at
1200 bps with a 75 bps back channel.
V.27ter
An ITU-T standard for facsimile operations that
specifies modulation at 4800 bps, with fallback to
2400 bps.
V.29
An ITU-T standard for facsimile operations that
specifies modulation at 9600 bps, with fallback to
7200 bps.
V.32
An ITU-T standard for modem communications at
9600 bps and 4800 bps. V.32 modems fall back to
4800 bps when line quality is impaired.
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