Zypcom Z34-PC, User Manual

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Appendix D-6
D
Duplex
A communication system which is capable of
communicating in both directions can be half duplex or
full duplex. Half duplex allows communication in both
directions, but only one direction at a time. Full duplex
allows data to be transmitted in two directions
simultaneously.
Off-hook
Picks up a telephone receiver. You take the modem off-
hook to dial or answer, and it remains off-hook while
you are connected.
On-hook
Hangs up a telephone receiver. You are not connected
to the Telephone Central Office when the modem is on-
hook.
DTMF
Dual-Tone-Multi-Frequency. The use of two
simultaneous audio band tones for dialing, touch-tones.
CCITT
Acronym for the International Telegraph and Telephone
Consultative Committee. An international organization
that decides upon recommended communication
protocol standards. Also, see ITU-T.
ITU-T
International Telecommunication Union-Telecom.
Formerly CCITT.