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

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