USRobotics V.34 - Manual (Page 222)

COURIER HIGH SPEED MODEMS
Glossary J-13
Throughput
The amount of actual user data transmitted per second without
the overhead of protocol information such as Start and Stop bits
or frame headers and trailers. Compare characters per second.
Transmission Rate
Same as Bit Rate.
V.17
An ITU-T standard for facsimile operations that specifies
modulation at 14.4K bps, with fallback to 12K bps.
V.21

Fax
An ITU-T standard for facsimile operations at 300 bps. U.S.
Robotics or compatible fax devices then transmit or receive at
higher speeds.
V.21

Modem
An ITU-T standard for modem communications at 300 bps.
Modems made in the U.S. or Canada follow the Bell 103 stan-
dard. However, the modem can be set to answer V.21 calls
from overseas.
V.22
A 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.
V.23
An ITU-T standard for modem communications at 1200 bps
with a 75 bps back channel. Used in the U.K.