Mobile carriers may have much larger market areas, and can assign or accept numbers from any area within the region.
In many telephone administrations, cell phone telephone numbers are in organized in prefix ranges distinct from land line service, which simplifies mobile number portability, even between carriers.
The number contains the information necessary to identify uniquely the intended endpoint for the telephone call.
Each such endpoint must have a unique number within the public switched telephone network.
For most countries, this is followed by an area code or city code and the subscriber number, which might consist of the code for a particular telephone exchange.
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.
In Canada, which shares the same country code with the U. Local number portability (LNP) allows a subscriber to request moving an existing telephone number to another telephone service provider.
Number portability usually has geographic limitations, such as an existing local phone company only being able to port to a competitor within the same rate centre.Telephone numbers are assigned within the framework of a national or regional telephone numbering plan to subscribers by telephone service operators, which may be commercial entities, state-controlled administrations, or other telecommunication industry associations.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.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.As telephone systems have grown and interconnected to encompass worldwide communication, telephone numbers have become longer.For example, a telephone number in North America consists of a three-digit area code, a three-digit central office code, and four digits for the line number.