ETN
Issue 1.0 May 2003
405
electronic tandem
network (ETN)
A tandem tie-trunk network that has automatic call-routing capabilities based on the
number dialed and the most preferred route available. Each switch in the network is
assigned a unique private network office code (RNX), and each voice terminal is
assigned a unique extension.
Electronics Industries
Association (EIA)
A trade association of the electronics industry that establishes electrical and
functional standards.
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
on page 395.
ESF
Extended superframe format
ESPA
European Standard Paging Access
ETA
Extended Trunk Access; also Enhanced Terminal Administration
ETN
Electronic tandem network