Telephone numbering plan

Area codeCalling codearea codesTelephone codeArea code(s)Opentelephone area codenumbering planClosedclosed telephone numbering plan
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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List of country calling codes

Country CodeDialing codeTelephone 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.

Telephone numbers in the United Kingdom

+44dialling code0141
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 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.

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.

E.164

e164.arpae164.orgcountry code
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 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.

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.

Telephone exchange

exchangescentral officeexchange
The first few digits of the subscriber number typically 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.

Numbering scheme

numberingnumbering systemnumbered
A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints.
Numbering plans by country

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.

E.214

In public land mobile networks, the E.212 numbering plan is used for subscriber identities, e.g., stored in the GSM SIM, while E.214 is used for routing database queries across PSTN networks.
In mobile telecommunications network routing, E.214 is one of three prevailing numbering plans used for delivering mobility management related messages.

Overlay plan

overlayoverlaidoverlay area code
In North America ten-digit dialing is required in areas with overlay plans.
In telecommunications, an overlay is an additional area code that is introduced into the same geographic region already served by the North American Numbering Plan (NANP).

Telephone numbers in Germany

+49Germany49
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 United Kingdom.
Germany has an open telephone numbering plan.

Trunk prefix

trunk code8city or region
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 portabilityportedport
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.

Toll-free telephone number

toll-freetoll-free number800 number
+800 – International Freephone (UIFN)
A toll-free, Freecall, Freephone, 800, 0800 or 1-800 number is identified by a dialing prefix similar to a geographic area code, such as 800.

Local access and transport area

LATALATA codeLATAs
LATA boundaries tend to be drawn around markets, and not necessarily along existing state or area code borders.

Global title

Global Title Translation
Numbering plans also decide on the routing of Signaling System 7 (SS7) signaling messages as part of the Global Title.
The structure of a global title for ITU-T applications is officially defined in ITU-T Recommendation Q.713, and further extended in the supporting numbering plan standards.

Premium-rate telephone number

premium rate900 number1-900
While the billing is different, calls are usually routed the same way they are for a toll-free telephone number, being anywhere despite the area code used.

Telephone numbers in Italy

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

Public switched telephone network

PSTNtelephone networkpublic telephone network
In public land mobile networks, the E.212 numbering plan is used for subscriber identities, e.g., stored in the GSM SIM, while E.214 is used for routing database queries across PSTN networks. 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.

Area codes 306 and 639

306306 / 639306/639
For example, to call a number in Regina in area code 306 (Regina and the rest of the province of Saskatchewan are also served by the overlay code 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+
By convention, international telephone numbers are indicated by prefixing the country code with a plus sign, which is meant to indicate that the subscriber must dial the international dialing prefix in the country from which the call is placed.
It is synonymous with international access code or exit code. The international call prefix is part of the telephone numbering plan of a country for calls to another country.

London

London, EnglandLondon, UKLondon, United Kingdom
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's canonical address format
In these situations, the ITU-T Recommendation E.123 suggests to list the area code in parentheses, signifying that in some cases the area code is optional or is not 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.

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.

Business telephone system

PBXprivate branch exchangekey telephone system
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.
In the first numbering plan the PBX maps one-to-one with the numbering plan of the public switched telephone network, e.g. the PBX is assigned all numbers 234-5000 to 234-5999 (1000 devices), and the public switched telephone network treats it as a normal internal switching exchange.