User`s manual

U.S. Robotics I-modem Command Reference
Glossary • Page G-13
CSD
See circuit-switched data.
CSV
See circuit-switched voice.
CSV/D
Alternating circuit-switched voice and data. See circuit-switched voice and circuit-
switched data.
ÒCustomÓ
AT&TÕs call-control signaling protocol that was implemented before the advent of NI-1.
cyclic redundancy check (CRC)
An error-detection technique consisting of a cyclic algorithm performed on each block or
frame of data by both sending and receiving modems. The sending modem inserts the
results of its computation in each data block in the form of a CRC code. The receiving
modem compares its results with the received CRC code and responds with either a posi-
tive or negative acknowledgment. In the ARQ protocol
imple-mented in U.S. Robotics