Telephone number
Modern smart phones have added a built-in layer of abstraction whereby individuals or businesses are saved into a contacts application (akin to an electronic address book) and the numbers no longer have to be written down or memorized.
Telephone numbers were first used in 1879 in Lowell, Massachusetts, when they replaced the request for subscriber names by callers connecting to the switchboard operator.
[3][4] When telephone numbers were first used they were very short, from one to three digits, and were communicated orally to a switchboard operator when initiating a call.
In addition to telephones, they have been used to access other devices, such as computer modems, pagers, and fax machines.
With landlines, modems and pagers falling out of use in favor of all-digital always-connected broadband Internet and mobile phones, telephone numbers are now often used by data-only cellular devices, such as some tablet computers, digital televisions, video game controllers, and mobile hotspots, on which it is not even possible to make or accept a call.
For each large metro area, all of these lines will share the same prefix (such as 404-741-xxxx in Atlanta and 305-550-xxxx in Miami), the last digits typically corresponding to the station's frequency, callsign, or moniker.
ITU-T recommendation E.123 describes how to represent an international telephone number in writing or print, starting with a plus sign ("+") and the country code.
The 3GPP standards for mobile networks provide a BCD-encoded field of ten bytes for the telephone number ("Dialling Number/SCC String").
[6] This scheme allows to extend the subscriber number with a maximum of 20 digits by additional function values to control network services.
[7] The format and allocation of local telephone numbers are controlled by each nation's respective government, either directly or by sponsored organizations (such as NANPA in the US or CNAC in Canada).
Number portability usually has geographic limitations, such as an existing local telephone company only being able to port to a competitor within the same rate centre.
In a few large US cities, as well as many points outside North America, local calls are not flat-rated or "free" by default.
Charles Williams, Jr., owned a Boston shop where Bell and Watson made experiments and later produced their telephones.
[8] In the late 1870s, the Bell interests started utilizing their patent with a rental scheme, in which they would rent their instruments to individual users who would contract with other suppliers to connect them; for example from home to office to factory.
Western Union and the Bell company both soon realized that a subscription service would be more profitable, with the invention of the telephone switchboard or central office.
He recommended the use of numbers for calling Lowell's more than 200 subscribers so that substitute operators might be more easily trained in such an emergency.
In most areas of North America, telephone numbers in metropolitan communities consisted of a combination of digits and letters, starting in the 1920s until the 1960s.
The "555" prefix was reserved for telephone company use and was only consistently used for directory assistance (information), being "555–1212" for the local area.
Names were convenient to use and reduced errors when telephone numbers were exchanged verbally between subscribers and operators.
In December 1930, New York City became the first city in the United States to adopt the two-letter and five-number format (2L-5N), which became the standard after World War II, when the Bell System administration designed the North American Numbering Plan to prepare the United States and Canada for Direct Distance Dialing (DDD), and began to convert all central offices to this format.
Some networks and equipment simply returned a number unobtainable, reorder or SIT (special information) tone to indicate an error.
It did exist in other cities, resulting in customers' having that number receiving random calls from people asking for God.
[12] Tommy Tutone's 1981 hit song "867-5309/Jenny" led to many unwanted calls by the public to telephone subscribers who actually were assigned that number.
