List of telephony terminology explained

This is a list of telephony terminology and acronyms which relate to telephony networks.

A

• Advanced Intelligent Network, (AIN), see also IN or Intelligent Network
• Automatic number announcement circuit (ANAC)
• Automated Attendant
• ACD - Automatic Call Distribution
• Articulation score

B

• Blue box - a device that was used to bypass the normal long-distance call switching tones typically used to obtain free calls.

C

• Call originator - (or calling party, caller or A-party) a person or device that initiates a telephone call by dialling a telephone number.
• Call waiting - a system that notifies a caller of another incoming telephone call by sounding a sound in the earpiece.
• Called party - (or callee or B-party)
• Caller
• Calling party
• Conference call (multi-party call)
• COCOT
• Cutunexpected, and usually sudden, termination of call, line or service

D

• Dial peer
• Dial tone
• Distribution frame
• Dual-tone multi-frequency signaling (DTMF)

E

• Emergency telephone number
• End instrument
• Engset calculation
• Erlang unit

F

• Fax - (contraction of facsimile) a device connected to the telephone network to enable documents to be scanned and sent to a receiving fax machine
• Frame - A distribution frame, a set of open wiring racks where circuits are cross connected to trunks and equipment

H

• Handoff
• Handover
• Help desk
• Howler tone (see ROH tone)
• Hunt Group

I

• Infrastructure
• Intelligent Network (IN)
• Interface functionality
• Inside plant
• Intelligent Network Interface Device (iNID) - replaces the Network Interface Device outside a subscriber's house like when customers subscribe to AT&T's U-verse brand of services.
• Interactive voice response (IVR)
• ISDN User Part (ISUP)

L

• Line
• Local loop
• Long-distance operator

O

• On-premises wiring
• Operator assistance
• Outside plant

P

• Patch-through access
• Permanent signal
• Person-to-person
• Plain old telephone service, or "POTS"
• Public Switched Telephone Network (PSTN)
• Pupinization

R

• Receiver Off-Hook tone (ROH)
• Red telephone box
• Red box
• Regional Bell Operating Company (RBOC)
• Ringer equivalency number (REN)
• Ringing signal
• Rural radio service

S

• Smartphone
• Station-to-station
• Signalling System 7 (SS7)

T

• Tandem signaling
• Tandem switch
• Transaction Capabilities Application Part (TCAP)
• Telemarketing
• Telephone
• Telephone booth
• Telephone call
• Telephone card
• Telephone directory
• Telephone exchange
• Telephone tapping
• Teletraffic engineering
• Time Division Multiplexing (TDM)
• Trap and trace
• TWX

V

• Vertical service code
• Voicemail
• Voice over Internet Protocol (VoIP)

W

• Western Union
• Wide Area Telephone Service (WATS)
• WATS line
• Wireless network
• Wireless Telephony Applications Interface (WTAI)
• Wi-Fi

Z

• Zenith number

Acronyms

Acronym	Name	Notes
1ESS	Number 1 Electronic Switching System (Alcatel-Lucent)	US
1FR	Flat rate service	US
2G
2.5G
3G
4ESS	Number 4 Electronic Switching System (Alcatel-Lucent)
4WTS	Four-wire termination set	US
5ESS	Number 5 Electronic Switching System (Alcatel-Lucent)
ACD	Automatic Call Distribution/Director
ACTS	Advanced Coin Telephone Service	US
ADSL
ANI		US
AMA		US
BOK	Unblocking	UK
CCIS
CID
CLEC		US
CLI		Europe
CLID		UK
CTI
COSMOS
DDCO	Direct Dial Central Office (Opposite of DID)	US
DDD		US
DDI		UK
DECT
DID		US
	Digital Multiplex System (e.g. DMS-100)	Can
DNIS		US
DSL
DTMF
FDM
GPRS
GSM
GST	Ground Start Trunk	US
IDDD	International Direct Distance Dialing	US
IDF		US
ILEC		US
ISD		UK and India
ISDN
IVR	Interactive Voice Response (a.k.a. VRU)
KSU	Key Switching/System Unit	US
LST	Loop Start Trunk	US
MDF
MF		US
PABX		Europe
PBX		US
PMBX	Private Manual Branch eXchange	UK
POTS
PSTN
RCMAC		US
REN
SMS	Short Message Service (i.e. text messages)
SF	Single Frequency supervision tone (2600)	US
SIP	Session Initiation Protocol	US
SP Lock	Unlocking	UK
SS7
STD		UK and India
T-CXR	T-carrier (e.g. T-1)	US
TAPI
TR		US
TSPS
TXE	Telephone eXchange Electronic	UK
UAX	Unit Automatic eXchange	UK
VoIP		US
WAP
WATS		US
WTAI