Multi-Tech Systems RAS96 - Manual (Page 49)

5 E1 Daughter Card
CommPlete Communications Server 41
E1 Glossary
RAI : Remote Alarm Indication; a field of all ones (1) used as a “keep-alive” signal.
AMI : Alternate Mark Inversion; a type of line coding for E1 spans.
HDB3 : High Density Bipolar Order 3 Encoding.
CAS : Channel Associated Signaling. A form of circuit state signaling in which the
circuit state is indicated by one or more bits of signaling status sent repetitively and
associated with that specific circuit.
bps : Bits per second; the serial digital stream’s data rate (e.g., 2.048M bps equals
2,048,000 bits per second).
BPV : Bipolar Violation (two pulses of the same polarity in a row).
CEPT : Conference on European Posts and Telecommunications (a body that sets
telecommunications service and interface policies).
CFA : Carrier Failure Alarm; detection of a red (local) or yellow (remote) alarm.
CO : Central office (the telephone company switch; the other end of a local loop from the
CP).
CP : Customer premises (user or customer-related operations, as opposed to telephone
company-related operations).
CPE : Customer premises equipment (user’s communications equipment, as opposed to
telephone company-related equipment).
CSU : A communications device that terminates the local loop and provides a digital
interface to the E1 line.
DNIS digits: Dialed Number Identification Service. DNIS is a feature of R2MF E1 lines
that provides the number the caller dialed to reach the attached computer telephony
system (manual or automatic).
DS-0 : Digital Signal, level 0 (the 64K bps worldwide standard speed for PCM digitized
voice channels).
DS-1 : Digital Signal, level 1 (the standard speed for PCM digitized voice channels;
1.544M bps in North America; 2.048M bps in ITU standards).
DS-2 : Digital Signal, level 2 (the standard speed of four E1s used in Japan).
DS-3 : Digital Signal, level 2 (the standard speed of 28 E1s; 44.736M bps).
DSL : Digital Subscriber Line (an ISDN BRI line).
DSU : The digital communications device used to convert an RS-232 to DSX-1 interface.
E-1 : The European digital signal level 1; 2.048M bps.
ESS : Electronic Switching System (a CO switch).
Frame: A method of error control where bits are inserted into the data stream for the
receiving device to identify the time slots allocated to each sub-channel.
FXO : Foreign Exchange, Office; an interface at the end of a private line connected to a
switch that, along with FXS, allows the phones to act as if connected locally to the
main PBX, but without the cost.