User`s guide

56K Professional Message Modem 45
full duplex
These signals will flow in both directions at the same time over one line.
In microcomputer communications, may refer to the suppression of the
online
local echo
.
half duplex
These signals will flow in both directions, but only one way at a time. In
microcomputer communications, may refer to activation of the online
local echo
, which causes the modem to send a copy of the transmitted
data to the screen of the sending computer.
handset mode
The mode in which the telephone handset is used to playback voice
messages, record the personal message, and place voice calls.
hands-free mode
The mode in which the modem’s internal microphone and speaker are
used to play back voice messages, record the personal voice message,
and place voice calls.
Hz
Hertz is a frequency measurement unit used internationally to indicate
cycles per second.
ITU-T
An international organization that defines standards for telegraphic and
telephone equipment. For example, the Bell 212A standard for 1200-
bps communication in North America is observed internationally as ITU-
T
V.22
. For 2400-bps communication, most U.S. manufacturers
observe V.22bis. The initials ITU-T represent the French name. In
English it is known as the International Telegraph and Telephone
Consultative Committee.
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.