|
AA
|
Automated
Attendant |
|
AAR
|
Automatic
Alternate Routing (trunks and tie trunks) |
|
ac
|
Alternating
Current |
|
ACD
|
Automatic Call
Distributor (system) |
|
AIOD
|
Automatic
Identified Outward Dialing |
|
ALIT
|
Automatic Line
Insulation Test |
|
AMA
|
Automatic Message
Accounting (recorded by CO) |
|
AMI
|
Alternate Mark
Inversion (a T-carrier line coding) |
|
AMIS
|
Audio Messaging
Interchange Specification |
|
ANC
|
All Number Calling |
|
ANI
|
Automatic Number
Identification |
|
ARS
|
Automatic Route
Selection (sometimes limited to CO trunks including WATS) |
|
ATB
|
All Trunks Busy |
|
ATM
|
Asynchronous
Transfer Mode |
|
A/D
|
Analog to Digital
(coding) |
|
A law
|
T-carrier voice
coding (European) |
|
|
|
B
|
Bearer channel at
64 kBps (ISDN) |
|
Baud
|
Duration of a
single data signal which may represent one or more bits. |
|
BLF
|
Busy lamp field
(usually on PBX console) |
|
BPS
|
Bits per second.
Prefix K for kilo, M for mega |
|
BRI
|
ISDN Basic Rate
Interface (2B+D) |
|
CAMA
|
Centralized AMA |
|
CATV
|
CAble TV
(Originally Community Antenna Television) |
|
CAS
|
Centralized
Attendant System |
|
CBX
|
Computer Based
Exchange (trade mark) |
|
CCIS
|
Common Channel Interoffice Signaling |
|
CCITT
|
Comite Consultatif Internationale de Telegraphique et
Telephonique Changed to ITU-T in June, 1993 |
|
CCS
|
Hundred Call
Seconds (traffic unit). |
|
CCSA
|
Common Control
Switching Arrangement (tie-trunk network) |
|
CD
|
Compact Disk |
|
CDO
|
Community Dial
Office |
|
CDR
|
Call Detail
Recording (at PBX) |
|
CENTREX
|
PBX service plus
DID and IOD |
|
CENTREX CO
|
Centrex provided
by a central office switch |
|
CENTREX CU
|
Centrex provided
by a PBX on the customer's premises |
|
CEMF
|
Counter
Electromotive Force |
|
CGA
|
Carrier Group
Alarm |
|
CI
|
Concentrator
Identifyer (for telephone answering bureaus). |
|
CO
|
Central Office |
|
COR
|
Class of
Restriction |
|
COS
|
Class of Service |
|
COV
|
Control Over Voice
(signaling channel to telephone set) |
|
CPE
|
Customer Premises
Equipment |
|
CPI
|
Computer to PBX
Interface (Northern Telecom) |
|
CRT
|
Cathode Ray Tube
(Usually implies a complete terminal. See VDT) |
|
CSP
|
Control Switching
Point |
|
CX
|
Composite
(signaling) |
|
|
|
D
|
Singaling channel
(ISDN) |
|
D(A)CS
|
Digital (Access
and) Cross-connect System |
|
DAMA
|
Demand Assignment
Multiple Access (Satellite) |
|
dB
|
Decibel (measure
of relative signal level) |
|
dBm
|
Level measured
relative to 1 milliwatt. |
|
dBRN
|
dB Reference Noise
(scale for measuring noise) |
|
dc
|
Direct Current |
|
DDC
|
Direct Department
Calling |
|
DDD
|
Direct Distance
Dialing |
|
DID
|
Direct Inward
Dialing |
|
DIL
|
Direct In Line |
|
DISA
|
Direct Inward
System Access |
|
DMI
|
Digital Multiplex
Interface (AT&T: early approach to PRI) |
|
DMS
|
Digital
Multiplexed System (Northern Telecom) |
|
DNIS
|
Dialed Number
Identification Service |
|
DOV
|
Data Over Voice |
|
DP
|
Dial Pulse |
|
DS0
|
Digital Signal 0 (64 kBps) |
|
DS1
|
Digital Signal 1 (24 DS0 channels) |
|
DSS
|
Direct Station
Selection (on a console) |
|
DTMF
|
Dual Tone
Multi-frequency |
|
DX
|
Duplex (signaling) |
|
D/A
|
Digital to analog
(decoding) |
|
|
|
EAS
|
Extended Area
Service |
|
E&M
|
Form of signaling |
|
EAX
|
Electronic
Automatic eXchange (trade mark) |
|
EKTS
|
Electronic Key
Telephone System |
|
ESS
|
Electronic
Switching System |
|
|
|
FADS
|
Force
Administration Data System |
|
FCG
|
False Cross and
Ground (matrix test) |
|
FDF
|
Fiber Distribution
Frame |
|
FDM
|
Frequency Division
Multiplexing |
|
FX
|
Foreign Exchange
(type of CO trunk) |
|
|
|
HOBIC
|
Hotel Billing
Information Center |
|
HU
|
High Usage (direct
trunk group) |
|
HU
|
Hang Up |
|
Hz
|
Hertz (Frequency,
or cycles per second) |
|
|
|
ID
|
Identification as
in Calling Number ID |
|
IDF
|
Intermediate
Distributing Frame |
|
ILI
|
Idle Line
Indicator (on switchboard) |
|
IN
|
Intelligent
Network |
|
IOD
|
Identified Outward
Dialing (may use operator) |
|
IPM
|
Impulses Per
Minute (interruption rate for call progress tones) |
|
IR
|
Voltage Drop
caused by current I through resistor R |
|
ISDN
|
Integrated
Services Digital Network |
|
ITI
|
Idle Trunk
Indicator (on switchboard) |
|
ITU-T
|
International
Telecommunications Union; -T stands for Telecommunications
Standardization Sector (formerly CCITT) |
|
|
|
JGF
|
Junctor Grouping
Frame |
|
|
|
kBps
|
Killobits per
second |
|
KP
|
Key Pulse
(unlocking signal in MF signaling) |
|
KPT
|
Key per Trunk
(type of PBX console) |
|
KSU
|
Key Service Unit
(for multibutton sets) |
|
KTU
|
Key Telephone Unit
(for multibutton sets) |
|
|
|
LAN
|
Local Area Network |
|
LATA
|
Local Access and
Transport Area |
|
LCD
|
Liquid Crystal
Display |
|
LED
|
Light Emitting
Diode |
|
LLF
|
Line Link Frame
(Crossbar) |
|
LSI
|
Large Scale Integration (device fabrication) |
|
LSI
|
Line Status
Indicator (like DSS without buttons) |
|
|
|
mA
|
milliampere, small
unit of electrical current |
|
mBps
|
Megabits per
second |
|
MDF
|
Main Distributing
Frame |
|
MF
|
Multi-frequency
(signaling) |
|
MIS
|
Management Information System (FADS) |
|
mS
|
Millisecond |
|
mu law
|
PCM coding
approach (North America, Japan) |
|
|
|
N
|
In numbering plan,
any digit 2-9 |
|
N11
|
Service codes such
as 911 for emergency |
|
NNX
|
Old form of office
code |
|
NXX
|
New form of office
code |
|
NT1
|
ISDN unit between
U and S/T interface (single line) |
|
NT2
|
Similar, but
serving multiple S/T interfaces (e.g. a PBX) |
|
|
|
OA&M
|
Operations,
Administration and Maintenance |
|
ONI
|
Operator Number
Identification |
|
OPS,X
|
Off Premises
Station, eXtension |
|
OR
|
Originating
Register (for DP, DTMF in XBAR systems) |
|
OSPS
|
Operator Services
Position System (AT&T) |
|
|
|
PA
|
Public Address
(loud speaker system often used for paging) |
|
PAM
|
Pulse Amplitude
Modulation |
|
Panel
|
Switching system
using motor driven switches |
|
PBX
|
Private Branch
Exchange |
|
PC
|
Personal Computer
(usually IBM-compatible) |
|
PCB
|
Printed Circuit
Board |
|
PCI
|
PBX to Computer
Interface (Northern Telecom; bit-robbed) |
|
PCM
|
Pulse Code Modulation |
|
PCS
|
Personal (Radio) Communications Service |
|
PMS
|
Property
Management System |
|
PNPN
|
Solid-state
breakdown device early used as a crosspoint |
|
PPS
|
Pulses Per Second |
|
PRI
|
ISDN Primary Rate
Interface (23B+D) |
|
PROM
|
Programmable ROM |
|
PWB
|
Printed Wire Board |
|
PWM
|
Pulse Width
Modulation |
|
|
|
QZ
|
IOD for PBXs prior
to Centrex |
|
|
|
RAM
|
Random Access
Memory (read-write) |
|
RLT
|
Release Link Trunk |
|
RMATS
|
Remote
Maintenance, Administration and Testing System |
|
RMS
|
Root Mean Square
(an ac signal equivalent to dc at the same value) |
|
ROH
|
Receiver Off Hook
(permanent signal) |
|
ROM
|
Read Only Memory
(still random access) |
|
Rotary
|
Switching system
using motor driven switches |
|
ROTS
|
Rotary Out Trunk
Switches |
|
RSU
|
Remote Switching
Unit |
|
|
|
S/T
|
ISDN interfaces
toward telephone (2 pair) |
|
SCR
|
Silicon Controlled
Rectifier |
|
SF
|
Single Frequency
(supervision) |
|
SLC
|
Subscriber Loop
Carrier |
|
SMDR
|
Station Message
Detail Recording (calls from telephones only) |
|
SNA
|
Systems Network
Architecture (IBM data protocol) |
|
SS7
|
CCITT Signaling
System Number 7 (form of CCIS) |
|
SPC
|
Stored Program
Control |
|
ST
|
Start, in MF
pulsing |
|
STP
|
Signal Transfer
Point (in CCIS) |
|
SXS
|
Step By Step
(Strowger method of automatic switching) |
|
|
|
T
|
Designation for
PCM digital carrier systems |
|
TASI
|
Time Assignment
Speech Interpolation |
|
TDF
|
Trunk Distributing
Frame |
|
TDM
|
Time Division
Multiplexing |
|
TLF
|
Trunk Link Frame
(Crossbar) |
|
TLP
|
Transmission Level
Point |
|
TOPS
|
Traffic Operator
Position System |
|
TSPS
|
Traffic Service
Position System |
|
T,R
|
Sometimes Tip,
Ring (conductors of a pair); Sometimes Transmit, Receive (in
block diagrams) |
|
TSI
|
Time Slot
Interchanger |
|
TST
|
Time Space Time
(form of digital switching matrix) |
|
TTY
|
Teletypewriter |
|
TUR
|
Traffic Usage
Recorder |
|
|
|
U
|
FCC-created ISDN
interface between telco and NT1/2 (one pair) |
|
UCD
|
Uniform Call
Distribution (feature) |
|
UNA
|
Universal Night
Answer |
|
UPS
|
Uninterruptable
Power Source |
|
|
|
V,H
|
Vertical,
Horizontal sides of MDF |
|
V,H
|
Coordinates used
to calculate trunk or call distance |
|
VDT
|
Video Display
Terminal (see also CRT) |
|
VLSI
|
Very Large Scale
Integration |
|
VNL
|
Via Net Loss
(Minimum trunk loss to control echo) |
|
|
|
WATS
|
Wide Area
Telecommunication Service |
|
|
|
X
|
In numbering plan,
any digit |
|
XBAR
|
Crossbar |
|
X-Y
|
Form of SXS
switching marketed by Stromberg Carlson |
|
|
|
1A2
|
Multiline
telephone system with switching in sets |
|
1ESS
|
No. 1 Electronic
Switching System |
|
3CL
|
AT&T toll
switchboard. L signified "low" for regular chairs |
|
2B1Q
|
Two binary digits
coded into one quarternary signal |
|
5XBAR
|
No. 5 Crossbar
Switching System |
