A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks.
United States telephone numbers often included letter prefixes and telephone exchange names, which were more easily memorable for users than long digit sequences.
A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices for data transmission via the public switched telephone network (PSTN), or other public and private networks. Modern smart phones have added a built-in layer of abstraction whereby individuals or businesses are saved into a contacts application and the numbers no longer have to be written down or memorized.
A Swiss rotary telephone dial from the 1970s showing the telephone's number (94 29 68), along with those of various local emergency services
Telephone numbers for sale in Hong Kong
A business card from Richard Nixon's first Congressional campaign in 1946; his telephone number can be seen as "Whittier 42635"
Face of a 1939 rotary dial showing a 2L-4N style alphanumeric telephone number LA-2697.
