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Glossary and Abbreviations
Issue 5 January 1998 GL-21555-230-024
emergency transfer
If a major system failure occurs, automatic transfer is initiated to a group of telephones capable of
making outgoing calls. The system operates in this mode until the failure is repaired and the
system automatically returns to normal operation. Also called power-failure transfer.
EMI
Electromagnetic interference
end-to-end signaling
The transmission of touch-tone signals generated by dialing from a voice terminal to remote
computer equipment. These digits are sent over the trunk as DTMF digits whether the trunk
signaling type is marked as tone or rotary and whether the originating station is tone or rotary.
Example: a call to a voice-mail machine or automated-attendant service. A connection is first
established over an outgoing trunk. Then additional digits are dialed to transmit information to be
processed by the computer equipment.
enhanced private-switched communications service (EPSCS)
An analog private telecommunications network based on the No. 5 crossbar and 1A ESS that
provides advanced voice and data telecommunications services to companies with many
locations.
EPN
Expansion-port network
EPROM
Erasable programmable read-only memory
EPSCS
Enhanced Private Switched Communications Services
ERL
Echo return loss
Erlang
A unit of traffic intensity, or load, used to express the amount of traffic needed to keep one facility
busy for one hour. One Erlang is equal to 36 CCS. See also CCS or hundred call seconds.
ESF
Extended superframe format
ESPA
European Standard Paging Access
ETA
Extended Trunk Access; also Enhanced Terminal Administration
ETN
Electronic tandem network
ETSI
European Telecommunications Standards Institute
expansion archangel (EAA)
A network-control microprocessor located on an expansion interface (EI) port circuit pack in an
expansion port network. The EA provides an interface between the EPN and its controlling
switch-processing element.