Specifications

C-8
Reference Guide
Model No.
Running Head
EPROM
Electronic Programmable Read-Only Memory, stores firmware on plug-in modules of the
system.
ESF
Extended Superframe (24-frame sequence for a T1 line; consists of two superframes)
ESS
Electronic Switching System
E&M
Earth and Magnetic, or recEive and transMit. The signaling leads on inter-switch voice
connections.
E&M Card
An E&M voice card for this system.
F4
Four-frame multiframe structure used in T1 signals.
FAS
Frame Alignment Signal
FCC
Federal Communications Commission
FDL
Facility Data Link, consists of every other framing bit of an extended T1 superframe. The FDL
is used to convey performance data, line test/loopback status, and other parameters for an
ESF-framed T1 line. The FDL rate is 4 kHz.
FOTS
Fiber Optics Transmission Systems
frame
A delineated assembly of information, consisting of one sequence of 24 encoded channel
samples (T1) or 32 channel samples (E1).