3Com 56k User's Manual And Reference page 42

LAPM
Link Access Procedure for Modems is an error-
control protocol defined in ITU-T
Recommendation V.42. Like the MNP protocols,
LAPM uses cyclic redundancy checking (CRC)
and retransmission of corrupted data (ARQ) to
ensure data reliability.
local echo
A modem feature that enables the modem to
display keyboard commands and transmitted data
on the screen. See command En.
MNP
Microcom Networking Protocol is an error-control
protocol developed by Microcom, Inc., and now in
the public domain. There are several different
MNP protocols, but the most commonly used one
ensures error-free transmission through error
detection (CRC) and retransmission of erred
frames.
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Glossary
modem
A device that transmits/receives computer data
through a communications channel such as radio
or telephone lines. It also changes signals received
from the phone line back to digital signals before
passing them to the receiving computer.
nonvolatile memory (NVRAM)
A user-programmable random access memory
which retains data when power is turned off. On
some modems, it includes four stored phone
numbers and the modem settings.
off/on hook
Modem operations that are the equivalent of
manually lifting a phone receiver (taking it off-
hook) and replacing it (going on-hook).