Telephone numbering plan

Area codeTelephone codearea codesPhone codeCalling codeArea code(s)telephone area codeOpennumbering planClosed
A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints.wikipedia
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Telephone number

phone numbertelephone numbersphone numbers
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 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.

List of country calling codes

Country CodeDialing codeCalling code
The standard defines a country calling code (country code) for each state or region which is prefixed to each national numbering plan telephone number for international destination routing.
Country codes are a component of the international telephone numbering plan, and are necessary only when dialing a telephone number to establish a call to another country.

E.164

E.163e164.arpae164.org
The International Telecommunication Union (ITU) has established a comprehensive numbering plan, designated E.164, for uniform interoperability of the networks of its member state or regional administrations.
E.164 is an international standard (ITU-T Recommendation), titled The international public telecommunication numbering plan, that defines a numbering plan for the worldwide public switched telephone network (PSTN) and some other data networks.

Telephone numbers in the United Kingdom

+440141dialling code
National telephone numbers are defined by national or regional numbering plans, such as the European Telephony Numbering Space, the North American Numbering Plan (NANP), or the UK number plan. Variable-length formats exist in multiple countries including: Argentina, Austria (1 to 4), Germany (2 to 5 digits), Japan (1 to 5), Mexico (2 or 3 digits), Peru (1 or 2), Syria (1 or 2) and the United Kingdom.
For this purpose Ofcom established a telephone numbering plan, known as the National Telephone Numbering Plan, which is the system for assigning telephone numbers to subscriber stations.

Numbering scheme

numbering systemnumberingnumbered
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 exchange

exchangescentral officeexchange
The first few digits of the subscriber number may indicate smaller geographical areas or individual telephone exchanges.
All central offices within a larger region, typically aggregated by state, were assigned a common numbering plan area code.

North American Numbering Plan

Area codeArea codesArea code(s)
National telephone numbers are defined by national or regional numbering plans, such as the European Telephony Numbering Space, the North American Numbering Plan (NANP), or the UK number plan. This concept was first developed for Operator Toll Dialing of the Bell System in the early 1940s, which preceded the North American Numbering Plan of 1947.
The North American Numbering Plan (NANP) is a telephone numbering plan that encompasses twenty-five distinct regions in twenty countries primarily in North America, including the Caribbean.

European Telephony Numbering Space

+388EU
National telephone numbers are defined by national or regional numbering plans, such as the European Telephony Numbering Space, the North American Numbering Plan (NANP), or the UK number plan.
With the intent of forming a trans-Europe numbering plan as an option (or then future movement) for anyone needing multi-national European telephone presence, the ITU allocated country calling code +388 as a subdivided, catch-all container for such services.

Public switched telephone network

PSTNpublic telephone networktelephone network
Telephone numbering plans are defined in each of administrative regions of the public switched telephone network (PSTN) and they are also present in private telephone networks.
The combination of the interconnected networks and the single numbering plan allow telephones around the world to dial each other.

Telephone numbers in Germany

+49GermanyGerman telephone numbering plan
Variable-length formats exist in multiple countries including: Argentina, Austria (1 to 4), Germany (2 to 5 digits), Japan (1 to 5), Mexico (2 or 3 digits), Peru (1 or 2), Syria (1 or 2) and the United Kingdom.
Germany has an open telephone numbering plan.

Overlay plan

overlayoverlaidoverlay area code
In North America ten-digit dialing is required in areas with overlay plans.
In telecommunications, an overlay plan is a telephone numbering plan that assigns multiple area codes to a geographic numbering plan area (NPA).

Trunk prefix

trunk codeTrunk access code8
When dialing a telephone number, the area code may be preceded by a trunk prefix (national access code), the international access code and country code.
Making a domestic (national) telephone call usually requires the dialing of a single or two-digit national trunk prefix preceding any area codes and the destination subscriber number.

Local number portability

number portabilityportported
The strict correlation of a telephone to a geographical area has been broken by technical advances, such as local number portability and Voice over IP service.
Canada, South Africa and the United States are the only countries that offer full number portability transfers between both fixed lines and mobile phone lines, because mobile and fixed line numbers are mixed in the same area codes, and are billed identically for the calling party, the mobile user usually pays for incoming calls and texts; in other countries all mobile numbers are placed in higher priced mobile-dedicated area codes and the originator of the call to the mobile phone pays for the call.

Telephone numbers in Italy

+39Italian telephone numbering planItaly
Internationally, an area code is typically prefixed by a domestic trunk access code (usually 0) when dialing from inside a country, but is not necessary when calling from other countries; there are exceptions, such as for Italian land lines.
The country code for calling Italy from abroad is 39.

Area codes 306 and 639

306Area code 306306 / 639
Area codes 306 and 639 are the telephone area codes in the Canadian province of Saskatchewan, encompassing the province.

List of international call prefixes

International Call Prefixinternational access code+
This reminds the subscriber to dial the international dialing prefix in the country from which the call is placed.
The international call prefix is part of the telephone numbering plan of a country for calls to another country.

Operator Toll Dialing

Nationwide Operator Toll Dialing
This concept was first developed for Operator Toll Dialing of the Bell System in the early 1940s, which preceded the North American Numbering Plan of 1947.
Initially this system involved step-by-step routings to set up each circuit, but later was improved by the development of area codes with machine translation which helped to standardize dialing across the network.

London

London, EnglandLondon, United KingdomLondon, UK
For example, a number in London may be listed as 020 7946 0321.
The London telephone area code (020) covers a larger area, similar in size to Greater London, although some outer districts are excluded and some places just outside are included.

E.123

Microsoft telephone number formatMicrosoft's canonical address format
In these situations, ITU-T Recommendation E.123 suggests to list the area code in parentheses, signifying that in some cases the area code is optional or may not be required.
Parentheses are used in national notation to indicate digits that are sometimes not dialed, such as area code in variable-length dialing numbering plans.

Business telephone system

PBXprivate branch exchangePABX
Many organizations have private branch exchange systems which permit dialing the access digit(s) for an outside line (usually 9 or 8), a "1" and finally the local area code and xxx xxxx in areas without overlays.
Each device connected to the PBX, such as a telephone, a fax machine, or a computer modem, is referred to as an extension and has a designated extension telephone number that may or may not be mapped automatically to the numbering plan of the central office and the telephone number block allocated to the PBX.

Toll-free telephone number

toll-freetoll-free number800 number
A toll-free, Freecall, Freephone, 800, 0800 or 1800 number is identified by a dialing prefix similar to a geographic area code, such as 909 (the area code that covers eastern Los Angeles County and southwestern San Bernardino County).

E.214

In mobile telecommunications network routing, E.214 is one of three prevailing numbering plans used for delivering mobility management related messages.

Dial plan

dialing plandialing proceduredialling plan
In contrast to numbering plans, which determine telephone numbers assigned to subscriber stations, dialing plans establish the customer dialing procedures, i.e., the sequence of digits or symbols to be dialed to reach a destination.
*Telephone numbering plan

Telephone exchange names

central office nametelephone exchangetelephone exchange name
Several systematic telephone numbering plans existed in various communities, typically evolving over time as the subscriber base outgrew older numbering schemes.

List of North American Numbering Plan area codes

List of NANP area codesList of North American area codesArea Codes
Each area is assigned a three-digit area code which is prefixed to each telephone number issued in its service area.