Phone Call Recorder

telephone exchange

In the field of telecommunications, a telephone exchange or central office houses equipment that is commonly known as simply a switch, which is a piece of equipment that connects phone calls. It is what makes phone calls "work" in the sense of making connections and relaying the speech information. The term exchange can also be used to refer to an area served by a particular switch. More narrowly, it can refer to the first three digits of the local number. In the three-digit sense of the word, other obsolete Bell System terms include office code and NNX. In the United States, the word exchange can also have the technical meaning of a local access and transport area under the Modification of Final Judgment (MFJ). In the past, the first two or three digits would map to a mnemonic exchange name, e.g. 869-1234 was formerly TOwnsend 9-1234, and before that (in some localities) might have been TOWnsend 1234 (only the capital letters and numbers being dialed). In December of 1930, New York City became the first locality in the United States to adopt the two-letter, five-number format; it remained alone in this respect until well after World War II, when other municipalities across the country began to follow suit (in some areas, most notably much of California, telephone numbers in the 1930s through early 1950s consisted of only six digits, two letters which began the exchange name followed by four numbers, as in DUnkirk 0799). Prior to the mid-1950s, the number immediately following the name could never be a "0" or "1;" indeed, "0" was never pressed into service at all, except in the immediate Los Angeles area (the "BEnsonhurst 0" exchange mentioned in an episode of the popular TV sitcom The Honeymooners was fictitious). In 1955, the Bell System attempted to standardize the process of naming exchanges by issuing a "recommended list" of names to be used for the various number combinations. In 1961, New York Telephone introduced "selected-letter" exchanges, in which the two letters did not mark the start of any particular name (example: FL 6-9970), and by 1965 all newly-connected phone numbers nationwide consisted of numerals only (Wichita Falls, Texas had been the first locality in the United States to implement the latter, having done so in 1958). Pre-existing numbers continued to be displayed the old way in many places well into the 1970s. A Chicago carpet retailer frequently advertised their number NAtional 2-9000 on WGN until the 1990s; not to mention, the number TYler 8-7100 for a Detroit construction company. Most of the United Kingdom had no lettered telephone dials until the introduction of Subscriber Trunk Dialling (STD) in 1958. Only the director areas (Birmingham, Edinburgh, Glasgow, Liverpool, London and Manchester) and the non-director areas adjacent to them had lettered dials, and the exchanges used the three-letter, four-number format until conversion to all-figure numbering in 1968.

List of telephony terms:

3gpp - a-law - abbreviated dialing - adsl - ani - answering machine - apn - automatic ring back - b-channel - baud - bell 202 modem - bit rate - bonding - bri - busy signal - cable modem - call-progress tones - call accounting - call capture - call forwarding - call originator - call park - call pick-up - call transfer - call waiting - call waiting deluxe - called party - caller id - caller id spoofing - calling party - carrier wave - cbr - ccitt - cdma - cdma2000 - cellular repeater - celp - channel - clec - clock rate - codec - collect call - conference - conference call - crc - csd - d-channel - data compression - device driver - dial-up - dial - dial tone - direct-inward-dialing - direct distance dialing - distinctive ring - dnis - dsl - dsp - dtmf - dtr - duplex - echo cancellation - edge - extension - fax - fcc - fdma - fidonet - follow-me - g.711 - g.723.1 - g.723 - g.726 - g.lite - gprs - gps - gsm - h.323 - harmonic - headphones - hscsd - hspda - iad - idsn - internet call waiting - isp - ivr - jack plug - local loop - long distance - microcontroller - mobile phone - modem - modulation - mu-law - music-on-hold - night service - off-hook - on-hook - pabx - pager - payphone - pbx - pcm - pots - prank call - precise tone plan - pstn - pulse dialling - push to talk - ring modulation - ring tone - ringback - ringing signal - rj11 - roaming - serial communications - serial port - signal noise - sim - simplex - sit - sms - softmodem - switchboard operator - tapi - tdma - telecommunications - telemarketing - telephone - telephone call - telephone card - telephone company - telephone exchange - telephone line - telephone number - telephone numbering plan - telephone operator - telephone switchboard - telephony - tts - twisted pair - umts - v.32 - v.32bis - v.34 - v.42bis - vbr - vertical service code - voicemail - voip - vox - wap - wav - wi-fi - wimax - wire