ADTRAN 25 manual Glossary

GLOSSARY

Dual-Tone Multifrequency (DTMF)

Industry terminology for touch-tone calling.

Emergency Transfer Unit (ETU)

Provides direct connection of designated Power Failure Transfer (PFT) registered voice terminals to the CO during a power failure or other service interruption.

E r l a n g

A traffic measuring unit that expresses the load of one or more traffic-generating devices (36 CCS equals 1 erlang—see CCS [Hundred Call Seconds]).

Extension Number

A 1- through 4-digit number assigned to each voice terminal and data endpoint in the system. Also see “Personal Dial Code.”

External Call

A connection between a system user and a party on the public telephone network or on a tie trunk. Also referred to as an outside c a l l .

Facility (Physical)

A transmission channel to another switching system (a Central Office, for example). By application, examples are:

●CO Trunks

●FX Trunks

●WATS Trunks

●OCC Trunks

●Tie Trunks

●DS1 Tie Trunks.

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