Telephone number

A sequence of digits assigned to a telephone service or destination and used to identify it when placing a call. Its structure can encode a country, region, network, or subscriber.

Telephone numbering plan: A system that assigns telephone numbers and defines their structure and use. It determines how telephone numbers are formed and allocated.
Call routing: The process of selecting network paths that carry a call to its destination. Dialed digits guide the network toward the telephone service identified by the number.
Telephone extension: A short number used to reach an internal destination within a private telephone system. Unlike a public telephone number, it usually works only after reaching the organization.
Caller ID: A telephone service that displays information about an incoming call's origin. It can present a telephone number to the recipient before the call is answered.
Telephone number privacy: The control of access to information linking telephone numbers with people or services. A number can expose personal or organizational contact details when published or shared.
International Telecommunication Union: A United Nations agency that coordinates global telecommunications standards and spectrum allocation. It standardizes country calling codes through its E.164 recommendation.
Number portability: The ability to keep a telephone number when changing service provider or location. Portability separates a number's identity from the provider currently serving it.
SIM card: A chip that identifies a subscriber to a mobile network and stores authentication information. A phone number identifies a reachable service, while a SIM authenticates network access.
Emergency telephone number: A short number used to contact emergency services, such as 911 or 112. It is a special, widely recognized number for urgent access to help.
Telephone numbering area: A geographic region served by a defined telephone numbering system or area code. Geographic numbering can associate a number with a place even when its user moves.

Linked from 5 pages