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 distributor 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 Technical terminology Telephony