Abbreviations and Acronyms

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a	atto (10-18)
A	amperes (current)
Å	angstrom
AAR	automatic alternate routing
AARTS	automatic audio remote test set
ABR	available bit rate
ABS	alternate billing services
ABSBH	average busy season busy hour
ac	alternating current access information
ACC	automatic callback calling
ACD	automatic call distributor
ac-dc	alternating current - direct current
ACG	automatic call gap
ACH	attempts per circuit hour
ACK	acknowledge character
ACM	address complete message
ACP	action point
ACSB	amplitude companded single-sideband
ACSE	association control service element
ACTEL	access telephone number
ACTL	access customer terminal location
ACTS	Advanced Communications Technology Satellite automated coin toll service
ACU	automatic calling unit
A-D	analog-to-digital
ADC	analog-to-digital converter analog-to-digital conversion
ADCCP	Advanced Data Communication Control Procedures
ADH	automatic data handling
ADMD	administration management domain
ADP	automatic data processing
ADPCM	adaptive differential pulse-code modulation
ADPE	automatic data processing equipment
ADPSSO	automatic data processing system security officer
ADS	auxiliary data system
ADU	automatic dialing unit
ADX	automatic data exchange
AECS	Aeronautical Emergency Communications System [Plan]
AERM	alignment error rate monitor
AES	Advanced Encryption Standard
AF	audio frequency
AFC	area frequency coordinator automatic frequency control
AFNOR	Association Francaise de Normalisation
AFRS	Armed Forces Radio Service
AGC	automatic gain control
AGE	aerospace ground equipment
AI	artificial intelligence action indicator
AIC	Automatic Intercept Center
AIG	address indicator group address indicating group
AIM	amplitude intensity modulation
AIN	advanced intelligent network
AIOD	automatic identified outward dialing
AIS	automated information system alarm indication signal automatic intercept system
AITS	acknowledged information transfer service
ASIC	application-specific integrated circuits
AJ	anti-jamming
AK	data acknowledgement (see also “ACK”)
ALBO	automatic line buildout
ALC	automatic level control automatic load control
ALE	automatic link establishment
ALGOL	Algorithmic Computer Language
ALS	application layer structure
ALU	arithmetic and logic unit
A/m	amperes per meter
AM	amplitude modulation
AMA	automatic message accounting
AMARC	automatic message accounting recording center
AMAT	automatic message accounting transmitter
AMC	administrative management complex
AME	amplitude modulation equivalent automatic message exchange
AMI	alternate mark inversion [signal]
AM/PM/VSB	amplitude modulation/phase modulation/vestigial sideband
AMPS	automatic message processing system advanced mobile phone system
AMPSSO	automated message processing system security officer
AMSC	American Mobile Satellite Corporation
AMTS	automated maritime telecommunications system
ANI	automatic number identification
ANL	automatic noise limiter
ANM	answer message
ANMCC	Alternate National Military Command Center
ANS	American National Standard
ANSI	American National Standards Institute
AP	anomalous propagation application process
APAB	all-primary / all-backup
APC	adaptive predictive coding
APCO	Association of Public Safety Communications Officials
APD, apd, a.p.d.	avalanche photodiode
APDU	application protocol data unit
API	application program interface
APL	average picture level
APND	all-primary / no-backup
APOT	additional point of termination
APK	amplitude phase-shift keying
APS	automatic protection switching
APSB	all-primary / some backup
ARP	address resolution protocol
ARPA	Advanced Research Projects Agency [now DARPA]
ARPANET	Advanced Research Projects Agency Network
ARQ	automatic repeat-request
ARS	automatic route selection
ARSR	air route surveillance radar
ARU	audio response unit
ASC	AUTODIN Switching Center access service company access service coordinator
ASC-EC	access service coordination exchange company
ASCII	American Standard Code for Information Interchange
ASE	application service element
ASG	access service group
ASELP	algebraic sum excited linear prediction
ASIC	application-specific integrated circuits
ASN.1	abstract syntax notation one
ASP	aggregated switch procurement application service part adjunct service point assignment source point
ASR	access service request airport surveillance radar automatic send and receive
ASR NO	access service request number
AT	access tandem
ATACS	Army Tactical Communications System
ATB	all trunks busy
ATCRBS	air traffic control radar beacon system
ATDM	asynchronous time-division multiplexing
ATE	automatic test equipment
ATIS	Alliance for Telecommunications Industry Solutions [formerly ECSA]
ATM	advanced testing method asynchronous transfer mode
ATN	account telephone number
ATRS	automated trouble reporting system
ATV	advanced television
au	astronomical unit access unit
AUI	attachment unit interface
AUTODIN	Automatic Digital Network
AUTOSEVOCOM	Automatic Secure Voice Communications Network
AUTOVON	Automatic Voice Network
AV	audiovisual
AVD	alternate voice/data
AWG	American wire gauge
AWGN	additive white Gaussian noise
AZ	azimuth
b	bit
B	bel byte
BAAD	band advance
balun	balanced to unbalanced
basecom	base communications
BASIC	beginners' all-purpose symbolic instruction code
BCC	block check character blocked calls cleared
BCD	binary-coded decimal binary-coded decimal notation blocked calls delayed
BCI	bit-count integrity
BCST	broadcast
Bd	baud
B8ZS	bipolar with eight-zero substitution
bell	BEL character
BER	bit error ratio
BERT	bit error ratio tester
BETRS	basic exchange telecommunications radio service
BEX	broadband exchange
BHMC	busy hour minutes of capacity
BIB	backward indicator bit
BIBR	backward indicator bit received
BIBT	backward indicator bit to be transmitted
BIBX	backward indicator bit expected
BIC	bearer identification code
BIH	International Time Bureau
BIP	bit interleaved parity
B-ISDN	broadband ISDN
bi-sync	binary synchronous [communication]
bit	binary digit
BIT	built-in test
BITE	built-in test equipment
BIU	bus interface unit
BLA	blocking acknowledgment message
BLER	block error ratio
BLO	blocking message
BLR	blocking/unblocking signal reception
BLS	blocking/unblocking signal sending
BNF	Backus Naur form
BOC	Bell Operating Company
BPSK	binary phase-shift keying
bpi	bits per inch bytes per inch
b/s  (formerly “bpi”)	bits per second
b/in (formerly “bps”)	bits per inch
BPSK	binary phase-shift keying
BPSS	basic packet switched service
BR	bit rate
BRAN	broadband radio access networks
BRI	basic rate interface
BS	base station
BSA	basic serving arrangement
BSBH	busy season busy hour
BSE	basic service element basic serving element
BSI	British Standards Institution
B6ZS	bipolar with six-zero substitution
BSM	backward setup message
BSN	backward sequence number
BSNR	backward sequence number received
BSNT	backward sequence number of next signal unit to be transmitted
BSP	Bell System Practices
BSS	base station system basic service set
B3ZS	bipolar with three-zero substitution
BTN	billed telephone number billing telephone number
BW	bandwidth
c	centi (10-2)
CA	communications assets
CACS	centralized alarm control system
CAD	call denial computer-aided design computer-aided drafting
CAG	combined access group
CAI	common air interface
CAISS	common air interfaces for satellite systems
CAM	computer-aided manufacturing
CAMA	centralized automatic message accounting
CAN	cancel character
CAP	competitive access provider customer administration panel
CARS	cable television relay service [station]
CAS	centralized attendant services call associated signaling
CASE	computer-aided software engineering computer-assisted software engineering
CATLAS	centralized automatic trouble locating and analysis system
CATV	cable TV community antenna television
CB	citizens band
CBA	changeback-acknowledgment signal
CBAN	Centrex billing account number
CBD	changeback-declaration signal
CBMS	computer based messaging system
CBN	common bonding network
CBX	computer branch exchange
CC	connection confirm country code
CCBS	completion of calls to busy subscribers
CCC	clear channel capability
C2	command and control
C3	command, control and communications
C3CM	C3countermeasures
C3I	command, control, communications and intelligence
CCA	carrier-controlled approach
CCD	charge-coupled device
CCH	connections per circuit per hour
CCIF	International Telephone Consultative Committee [a predecessor to the CCITT]
CIP	critical infrastructure protection
CCIR	International Radio Consultative Committee
CCIS	common-channel interoffice signaling
CCIT	International Telegraph Consultative Committee [a predecessor to the CCITT]
CCITT	International Telegraph and Telephone Consultative Committee {now ITU-T}
CCL	continuous communications link
CCMDS	common channel multipoint distribution system
CCO	continuity check outgoing
CC-PIC	customer changeable primary interexchange carrier
CCS	hundred call-seconds common channel signaling
CCSA	common control switching arrangement
CCS7	common channel signaling System #7
CCTV	closed-circuit television
CCW	cable cutoff wavelength
cd	candela
CD	collision detection, compact disk
CDA	call data accumulator
CDF	combined distribution frame cumulative distribution function
CDMA	code-division multiple access
CDO	community dial office
CDPD	cellular digital packet data
CDPSK	coherent differential phase-shift keying
CDR	call detail recording
CD ROM	compact disk read-only memory
CDT	call data transmitter control data terminal
CDU	central display unit
CE	connection endpoint
C-E	communications-electronics
CEF	cable entrance facility
CEI	comparably efficient interconnection connection endpoint identifier
CELP	code-excited linear prediction
CEP	circular error probable
CEPT	Conference Europeennes des Administrations des Postes et des Telecommunications
CESID	caller’s emergency service ID
CFA	carrier facility assignment connecting facility assignment
CFE	contractor-furnished equipment
CFL	call failure
CGAP	call gapping interval
CGB	circuit group blocking acknowledgment message
CGC	congestion control
cgs	centimeter-gram-second
CGH	charging message
CHOK	choke network
ChR	channel reliability
CI	customer installation
CIAS	circuit inventory and analysis system
CIC	carrier identification code circuit identification code content indicator code
CIF	common intermediate format
CIFAX	ciphered facsimile
CIGRR	common interest group on rating and routing
CINC	commander-in-chief
ciphony	ciphered telephony
CiR	circuit reliability
CITEL	Inter-American Telecommunications Commission
CK	check bit
CKLT	circuit link test
C/kT	carrier-to-receiver noise density
CKTACT	circuit activity
CKTID	circuit identification number
CL	connectionless
CLASS	custom local area signaling service
CLC	Carriers Liaison Committee
CLEI	common language equipment identification
CLNS	connectionless network service
CLP	cell loss priority (bit)
cm	centimeter
CMDF	combined main distributing frame combined main distribution frame
CMDS	centralized message data system
CMI	coded mark inversion
CMIP	Common Management Information Protocol
CMIS	common management information service
CMOS	complementary metal oxide substrate
CMR	call modification request message
CMRR	common-mode rejection ratio
CMRS	Commercial Mobile Radio Service
CMS	call management system
CNC	concentrator
CNCC	customer network control center
CNI	calling number identification
CNP	connection-not-possible signal
CNR	carrier-to-noise ratio combat-net radio
CNS	complementary network service connection-not-successful signal
C.O.	central office connection oriented
COAM	customer owned and maintained equipment
coax	coaxial cable
COBOL	common business oriented language
codec	coder-decoder
COG	centralized ordering group
COMINT	communications intelligence
COMJAM	communications jamming
compandor	compressor-expander
COMPUSEC	computer security
COMSAT	Communications Satellite Corporation
COMSEC	communications security
CONEX	connectivity exchange
CONUS	Continental United States
COP	Committee of Principals
COR	Council of Representatives
COT	customer office terminal continuity message
COTS	commercial off-the-shelf
CPAS	cellular priority access services cellular priority access system
CPC	call processing control calling party category circuit provision center
CPE	customer premises equipment
cpi	characters per inch
cpm	counts per minute
CPNI	calling party number identification
cps	characters per second cycles per second [deprecated]
CPU	central processing unit communications processor unit
C/R	command/response field bit
CR	channel reliability circuit reliability connection request
CRC	cyclic redundancy check
CRITICOM	Critical Intelligence Communications
CROM	control read-only memory
CRR	customer requested routing circuit reset reception
CRT	cathode-ray tube
CRTS	cellular radio telecommunications service
c/s	cycles per second [deprecated]
CSA	Canadian Standards Association
CSC	circuit-switching center common signaling channel
CSES	consecutive severely errored seconds
CSMA	carrier sense multiple access
CSMA/CA	carrier sense multiple access with collision avoidance
CSMA/CD	carrier sense multiple access with collision detection
CST	connection setup time
CSU	channel service unit customer service unit
CTIA	Cellular Telecommunications Industry Association
CTN	cut-through operation
CTS	clear to send
CTX	Centrex ® [service] clear to transmit
CUG	closed user group
CVD	chemical vapor deposition
CVSD	continuously variable slope delta [modulation]
cw	carrier wave continuous wave
CX	composite signaling
cxr	carrier
D*	specific detectivity
d	deci (101)
DA	directory directory assistance
D()	dispersion coefficient
da	deka (10)
D-A	digital-to-analog digital-to-analog converter
D/L	downlink
DACS	digital access and cross-connect system
DAI	dial address incoming
DAO	dial address outgoing
DAMA	demand assignment multiple access
D-AMPS	digital advanced mobile phone system
DARPA	Defense Advanced Research Projects Agency [formerly ARPA]
dB	decibel
dBa	decibels adjusted
dBa(F1A)	noise power measured by a set with F1A-line weighting
dBa(HA1)	noise power measured by a set with HA1-receiver weighting
dBa0	noise power measured at zero transmission level point
DBAS	database administration system
dBc	dB relative to carrier power
dBm	dB referred to 1 milliwatt
dBm(psoph)	noise power in dBm measured by a set with psophometric weighting
DBMS	database management system
dBmV	dB referred to 1 millivolt across 75 ohms
dBm0	noise power in dBm referred to or measured at 0TLP
dBm0p	noise power in dBm0 measured by a psophometric or noise measuring set having psophometric weighting
dBr	power difference in dB between any point and a reference point
dBrn	dB above reference noise
dBrnC	noise power in dBrn measured by a set with C-message weighting
dBrnC0	noise power in dBrnC referred to or measured at 0TLP
dBrn(f1-f2)	flat noise power in dBrn
dBrn(144-line)	noise power in dBrn measured by a set with 144-line weighting
DBSN	direct broadcast satellite network
dBv	dB relative to 1 V (volt) peak-to-peak
dBW	dB referred to 1 W (watt)
dBx	dB above reference coupling
dc	direct current
DC	disconnect code
DCA	Defense Communications Agency (now DISA)
DCE	data circuit-terminating equipment digital channel equipment
DCF	data communication function
DCL	direct communications link
DCM	digital carrier module
DCN	data communications network
DCP	data collection processor duplex central processor
DCPSK	differentially coherent phase-shift keying
DCS	Defense Communications System
DCT	digital carrier trunk
DCTN	Defense Commercial Telecommunications Network
DCWV	direct-current working volts
DDD	direct distance dialing
DDN	Defense Data Network
DDS	digital data service digital data system
DEL	delete character
demarc	demarcation point
demux	demultiplex demultiplexing
dequeue	double-ended queue
DES	Data Encryption Standard
detem	detector/emitter
DEW	Distant Early Warning (Line)
DFI	digital facility interface
DFSK	double-frequency shift keying
DIA	Defense Intelligence Agency
DIC	digital interface controller
DID	direct inward dialing
DIF	digital interface frame
DIG	digital integrity group
DIN	Deutsches Institut für Normung
DIP	dual in-line package
DIS	Draft International Standard
DISA	Defense Information Systems Agency {formerly DCA}
DISC	disconnect disconnect command
DISN	Defense Information System Network
DISNET	Defense Integrated Secure Network
DIT	directory information tree
DIU	digital interface unit
DLA	Defense Logistic Agency
DLC	digital loop carrier Data Link control (layer)
DLCI	data link connection identifier
DLY DL	delay dial
DLE	data link escape character
DLP	Data Link protocol
DL TU	digital line / trunk unit
DM	degraded minute delta modulation disconnect(ed) mode
DMA	Defense Mapping Agency direct memory access
DME	distance measuring equipment
DMS	Defense Message System
DNA	Defense Nuclear Agency
DNHR	dynamic nonhierarchical routing
DNI	destination network identification
DNIC	data network identification code
DNPA	data numbering plan area
DNS	Domain Name System
DO	design objective
DoC	Department of Commerce
DOC	dynamic overload control
DOD	Department of Defense direct outward dialing
DODD	Department of Defense Directive
DODISS	Department of Defense Index of Specifications and Standards
DOD-STD	Department of Defense Standard
DOJ	Department of Justice
DOS	Department of State
DOT	Department of Transportation
DOV	data over voice
DP	demarcation point dial pulse
DPCM	differential pulse-code modulation
DPSK	differential phase-shift keying
DQDB	distributed-queue dual-bus [network]
DQPSK	differential quadrature phase-shift keying
DR	data receive
DRAM	dynamic random access memory
DRS	delayed release signal
DRSI	destination station routing indicator
DS	data speed digital signal direct support
DS0	digital signal 0
DS1	digital signal 1
DS1C	digital signal 1C
DS2	digital signal 2
DS3	digital signal 3
DS4	digital signal 4
DSA	dial service assistance
DSAM	double-sided amplitude modulation
DSB	double-sideband [transmission] Defense Science Board
DSB-RC	double-sideband reduced carrier transmission
DSB-SC	double-sideband suppressed-carrier transmission
DSC	digital selective calling
DSCS	Defense Satellite Communications System
DSDC	direct services dialing capability
DSE	data switching exchange
DSI	digital speech interpolation
DSL	digital subscriber line
DSN	Defense Switched Network
DSn	digital signal, level n
DSP	digital signal processing
DSR	data signaling rate
DSS	data station selector direct station selection