Telephone numbering plan
Encyclopedia
A telephone numbering plan is a type of numbering scheme
used in telecommunications to allocate telephone number
s to subscribers and to route telephone calls in a telephone network. A closed numbering plan, such as found in North America, imposes a fixed total length to numbers. An open numbering plan features variance in the length of telephone numbers.
A dial plan establishes the expected number and pattern of digits for a telephone number
. This includes country code
s, access codes, area codes and all combinations of digits dialed. For instance, the North American public switched telephone network
(PSTN) uses a 10-digit dial plan that includes a 3-digit area code and a 7-digit telephone number. Most PBXs support variable-length dial plans that use 3 to 11 digits. Dial plans must comply with the telephone network
s to which they connect.
s using patch cords
to connect one party to another. If a person wanted to make a phone call, in some phone systems he or she would pick up a phone and wind a crank on the side. In other systems the person would wind the crank first, then pick up the phone. The crank was a small generator that would light a lamp at the central office. An operator would see the light and insert their patch cord into a socket and assist the customer with the call connection. The operator would use patch cords to connect the caller to the person being called. If the party being called was in another exchange, the operator would use a patch cord to connect to another exchange where an operator elsewhere would finish the connection. As technology advanced, electro-mechanical switches were introduced and calls were made using rotary dial
s.
Initial use of area codes in the United States and Canada began in the late 1940s with large cities. By 1966, the system was implemented fully in both countries.
Area codes were assigned based on the length of time a rotary dial
phone took to dial the area code. Densely populated areas like New York City, Chicago, Los Angeles, and Detroit had huge incoming call volume and were assigned numbers (212
, 312
, 213
, 313
) that could be quickly dialed from a rotary dial phone. On a rotary dial phone low digits (1, 2, 3, 4) could dial quickly as the time the rotary dial took to return to the home position was minimal. High digit numbers (7, 8, 9, 0) on rotary dial phones took much longer to return to the home position and were usually used in less densely populated areas like rural Texas (915). This numbering strategy became unnecessary when touch-tone
phones arrived, as the tone allowed instant entry of digits.
The original set of North American area codes was unique. When the North American Numbering Plan
was first developed, logic circuits consisted of relays and vacuum tubes, and simplicity was mandatory. The second digit of all area codes was 0 or 1, while the second digit of the exchange triplet was never 0 or 1, thus facilitating readily the recognition whether the dialing of a full 10-digit number was in progress or whether the user was dialing only a local number. In this coding scheme, a leading 1 indicating long distance, or out of the area code call, was not necessary. In some regions, local numbers were 7 digits (occasionally less), but a toll call within the area code required a preceding “1”. This told the subscriber that the call being placed was a toll call. Area Code 617 in eastern Massachusetts used this system in the early 1970s, while the Chicago area (Area Code 312) did not. In the Chicago Area, one could call the Boston area by dialing only 10 digits, while in Boston, to call Chicago, one would be required to use 11 digits (preceding the 10 digits with a “1”)
By the 1990s, the mechanical Central Office Switches were rapidly being replaced with ESS machines (Electronic Switching Systems), and the Area Code logic was no longer necessary. The need for more telephone numbers was increasing rapidly, and the NANPA (North American Numbering Plan Administration) was running out of “n0n” and “n1n” combinations. This Area Code scheme was abandoned, with the result that former Area Code only numbers could now be Exchanges, and former Exchange only numbers could now be Area Codes. This caused a logic dilemma: The Switch had no way of knowing whether to expect 10 digits or 7 digits. The solution was simple. If a preceding “1” was entered (by dial and Touch-Tone key pad), then 10 more digits were expected. If the first digit entered was NOT a “1” only 7 digits were expected and the call would remain within area code. For a short while, in some area codes, one could enter the full 11 digits for a call within their own neighborhood or just enter the last 7 digits, and the call would be routed and billed identically.
Currently, because of Area Code overlays, nearly all metropolitan and many rural telephone calls require the full 11 digit entry to complete a telephone call.
numbering plan, though some PABXs (business telephone systems) have internal extensions.
The E.164
numbering plan for telephone
numbers includes:
Apart from the use of numbering plans for telephone numbers, they are also used in routing of SS7 signalling messages as part of the Global Title
. In public land mobile network
s, 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 the UK. These are necessary (for the most part) only when dialed from outside the code area, from mobile phones, and (especially within North America) from within overlay plan
s. Area codes usually indicate geographical areas within one country that are covered by perhaps hundreds of telephone exchanges, although the correlation to geographical area is becoming obsolete.
The area code is usually preceded in the dial string by either the national access code
("0" for many countries, "1" in USA and Canada) or the international access code and country code. However, this is not always the case, especially when 10-digit dialing is used. For example, in Montreal, Quebec, where area codes 514 and 450 are currently in use, users dial 10-digit number (ex 514 555 1234), dialing a 1 before this results in a recording advising not to dial a 1 as it is a local call. For non-geographic numbers, as well as mobile telephones outside of the North American Numbering Plan area, the "area code" does not correlate to a particular geographic area.
Area codes are often quoted including the national access code, for example a number in London: 020 8765 4321. Users must then correctly interpret the "020" as the code for London. If calling from another number in London they merely dial 8765 4321, or if dialing from another country, drop the "0" and dial: +44 20 8765 4321.
000 area codes
are sometimes used in the United States by telemarketers and VoIP services. They are only used for outgoing calls, and can not be dialed.
Area codes were introduced in the United States by the Bell System
, in 1947. The first direct dial long distance call
occurred in 1951.
s. In mobile networks they may indicate a network provider in case the area code does not. Callers from a number with a given area/country code usually do not need to (but optionally may) include the particular area/country code in the number dialed, which enables shorter "dial strings" to be used. Devices that dial phone numbers automatically can include the full number with area and access codes, since there is no additional annoyance related to dialing extra digits.
(ITU) has attempted to promote common standards among nation states, numbering plans take different formats in different parts of the world. For example, the ITU recommends that member states adopt 00 as their international access code. However, as these recommendations are not binding on member states, some have not, such as the United States
, Canada
, and other countries and territories participating in the North American Numbering Plan
.
The international numbering plan establishes country codes, that is, area codes that denote nations or groups of nations. The E.164
standard regulates country code
s at the international level and sets a maximum length limit on a full international phone number (15 digits). However, it is each country's responsibility to define the numbering within its own network. As a result, regional area codes may be:
area codes are normally charged at a lower rate than outside the area code. This is not necessarily the case in the United States or Canada where rates are determined by the distance between rate centers. In most United States and Canadian locations area codes cover a sufficiently large territory that different rates will apply within the same area code determined by the distance between rate centers. Each rate center also has a local calling plan which determines which other rate centers, regardless of distance, are a local call. The area code plus the first three digits following the area code (the NPA-NXX) defines the rate center for any given telephone number. Multiple NPA-NXX combinations, often in different area codes, comprise each rate center, and each rate center is assigned a geographic point known as the rate center's V&H coordinates. The tariff distance in miles between any two rate centers may be calculated using by this formula:
.
Calls between nearby rate centers in different area codes may be cheaper (or even free local calls) as compared to calls to more distant rate centers in the same area code. Rates are set in zones of 0-6 mi, 6-12 mi, and so on, with these bands determined on a state-by-state basis for intrastate calls (calls within the same state) and determined by federal regulation for interstate calls (calls which cross a state line). As a specific example, callers in the Falls Church, Virginia, rate center (officially named "Washington Zone 17, VA"--example numbers beginning with 703-534, V=5636, H=1600) may make untimed local calls to 31 other nearby rate centers in Virginia, Maryland, and the District of Columbia in area codes 703, 571, 202, 301, and 240, while calls to distant locations in 703 such as Manassas and Haymarket, VA are charged as long distance.
Calls within a state [regulated by that state's public utilities commission] are often higher than rates to call more distant locations in some other state [regulated by the Federal Communications Commission
]. The partial deregulation and introduction of competition for long distance phone services has established other methods of determining call pricing that do not necessarily follow the traditional model. Each year, more customers switch to a fixed rate, "all-you-can-dial" plan covering the state, the United States, or all North America generally (as of May 2008 and exclusive of taxes) for approximately $30 per month. Competition with cable telephony
and Voice over Internet Protocol services have helped drive the cost of service down for residential and business customers.
Special area codes are generally used for free
, premium rate
, mobile phone
systems (in countries where the mobile phone system is caller pays) and other special rate numbers. There are however some exceptions, in some countries (like Egypt
), calls are charged at the same rate regardless of area and in others (like the UK
) an area code is occasionally treated as two parts with different rates.
, some typical dial plans include:
Many corporate telephone systems use a dialing prefix, typically the digit 9, to obtain a line to the public switched telephone network.
, the following dialing plans can be found:
In Australia, the digit 0 is used to obtain a line to the public switched telephone network.
Recommendation E.123
. The area code is prefixed by a trunk code (usually "0"), which (apart from rare cases such as Italian land lines) is omitted when calling from outside the country.
To call a number in Sydney, Australia
for example:
Note that the "+" is not dialed, it signifies that first the international access code must be dialed, followed by the country code, in this case 61, followed by the number. When using a mobile telephone to place a call, all GSM phones and many models using other technologies do allow the + to be entered and this is internally converted to the correct access code, based on caller location, as the call is made.
New Zealand
has a special case of an open dialing plan. While most nations require the area code to be dialed only if it is different, in New Zealand, one needs to dial the area code if the phone is outside the local calling area. For example, the town of Waikouaiti
is in the Dunedin
City Council jurisdiction, and has phone numbers (03) 465 7xxx. To call the city council in central Dunedin (03) 477 4000, residents must dial the number in full including the area code even though the area code is the same, as Waikouaiti and Dunedin lie in different local calling areas (Palmerston
and Dunedin respectively)
In the United States
, Canada
, and other countries or territories using the North American Numbering Plan
(NANP), the trunk code is '1', which is also (by coincidence) the country calling code. The same rule also applies in many parts of the NANP, including all areas of Canada that still have an open dialing plan. This is not universal, as there are locations within the United States that allow long distance calls within the same area code to be dialed as seven digits. In Canada, the trunk code (also known as the long distance access code) must also be dialed along with the area code for long distance calls even within the same area code. For example, to call a number in Regina
:
To call a number in San Francisco, California
the dialing procedure will vary:
However, in parts of North America, especially where a new area code overlays an older area code, dialing the area code, or 1 + the area code, is now required even for local calls, which means that the NANP is now closed in certain areas and open in others. Dialing from mobile phones is different in the U.S., as the trunk code is not necessary, although it is still necessary for calling all long distance numbers from a mobile phone in Canada. (Most mobile phones today can be programmed to automatically add a frequently-called area code as a prefix, allowing calls within the desired area to be dialed by the user as seven-digit numbers, though sent by the phone as 10-digit numbers.)
In some parts of the United States, especially northeastern states such as Pennsylvania
served by Verizon Communications
, the full 10-digit number must be dialed. If the call is not local, the call will not complete unless the dialed number is preceded by a 1. In this situation, where the area code is not optional, the area code is not enclosed in parentheses. Thus:
In areas served by AT&T
in California
, pre-recorded messages instruct customers that use of the local area code within the area code is not permissible and that only the xxx xxxx format is permitted.
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. This "feature" is unintentionally helpful for employees who reside in one area code and work in an area code with one, two, or three adjacent area codes. "1+" dialing to any area code by an employee can be done quickly, with all exceptions processed by the private branch exchange and passed onto the public switched telephone network
.
Open and closed dialing plans should not be confused with open and closed numbering plans. A closed numbering plan, such as found in North America, features fixed length area codes and local numbers. An open numbering plan, as found in assorted countries that have not yet standardized, features variance in length of area code or local number, or both. Closed dialing plans are rare where numbering plans are open.
For example, to call Oslo in Norway
before 1992, one would dial:
After 1992, this changed to a closed eight-digit numbering plan, e.g.:
Therefore in other countries, such as France
, Belgium
, Switzerland
, South Africa
and some parts of North America where the dialing plan is closed, the trunk code is retained for domestic calls, whether local or national, e.g.,
while some, like Italy, require the initial zero to be dialled, even for calls from outside the country, e.g.,
Further, there are locations with closed dialing plans in the NANP that require the full phone number including area code to be dialed for all calls, but the trunk code is required for only long distance calls, even in the same area code.
While the use of full national dialing is less user-friendly than using only a local number without the area code, the increased use of mobile phones, which can store numbers, means that this is of decreasing importance. It also makes easier to display numbers in the international format, as no trunk code is required—hence a number in Prague
, Czech Republic
, can now be displayed as:
as opposed to before September 21, 2002:
Some countries already switched, but trunk prefix re-added with the closed dialing plan, for example in Bangkok, Thailand before 1997:
has been switched in 1997:
Trunk prefix has re-added in 2001
s are usually issued with numbers in a special country calling code. For example, Inmarsat
satellite phones are issued with code +870, while Global Mobile Satellite System
providers, such as Iridium, issue numbers in country code +881 ("Global Mobile Satellite System") or +882 ("International Networks"). Some satellite phones are issued with ordinary phone numbers, such as Globalstar
satellite phones issued with NANP telephone numbers.
{| width="75%" cell spacing="1" cell padding="1" style="background-color: #efefef; border: solid 1px #eeeeee;"
|+ Dial Plan Syntax
|-
!
To specify a
!
Enter the following
!
Result
|-
| Digit
|0 1 2 3 4 5 6 7 8 9 *
| Identifies a specific digit (do not use #)
|-
| Range
|[digit-digit]
| Identifies any digit dialed that is included in the range
|-
| Range
|[digit-digit, digit]
| Specifies a range as a comma separated list
|-
| Wild card
|x
| x matches any single digit that is dialed
|-
| Wild card
|.
| . matches an arbitrary number of digits
|-
| Timer
|T
| Indicates that an additional time out period of 4 seconds should take place before automatic dialing starts
|-
|}
Some dial plan examples using the above syntax look as follows:
{| width="75%" cellspacing="1" cellpadding="1" style="background-color: #efefef; border: solid 1px #eeeeee;"
|+ Dial Plan Syntax Examples
|-
!
For calls to
!
Users dial
!
Dial plan
|-
| Internal Extension
|a two digit number
| xx
|-
| Local Number
|9 (if required for an outside line) and then a seven digit number
| 9xxxxxxxT
|-
| Emergency
|911
| 911
|-
| Local Operators
|9 (if required for an outside line) then 0
| 90T
|-
| Long Distance
|9 (if required), 1, area code and local number
| 91xxxxxxxxxx
|-
| International
|9 (if required), 011, any number of additional digits
| 9011x.T
|-
|}
messages. the following numbering plans and their respective Numbering Plan Indicator values have been defined:
Numbering scheme
There are many different numbering schemes for assigning nominal numbers to entities. These generally require an agreed set of rules, or a central coordinator. The schemes can be considered to be examples of a primary key of a database management system table, whose table definitions require a...
used in telecommunications to allocate telephone number
Telephone number
A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...
s to subscribers and to route telephone calls in a telephone network. A closed numbering plan, such as found in North America, imposes a fixed total length to numbers. An open numbering plan features variance in the length of telephone numbers.
A dial plan establishes the expected number and pattern of digits for a telephone number
Telephone number
A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...
. This includes country code
Country code
Country codes are short alphabetic or numeric geographical codes developed to represent countries and dependent areas, for use in data processing and communications. Several different systems have been developed to do this. The best known of these is ISO 3166-1...
s, access codes, area codes and all combinations of digits dialed. For instance, the North American public switched telephone network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
(PSTN) uses a 10-digit dial plan that includes a 3-digit area code and a 7-digit telephone number. Most PBXs support variable-length dial plans that use 3 to 11 digits. Dial plans must comply with the telephone network
Telephone network
A telephone network is a telecommunications network used for telephone calls between two or more parties.There are a number of different types of telephone network:...
s to which they connect.
History
In early telephone systems, connections were made in the central office by telephone operatorTelephone operator
A telephone operator is either* a person who provides assistance to a telephone caller, usually in the placing of operator assisted telephone calls such as calls from a pay phone, collect calls , calls which are billed to a credit card, station-to-station and person-to-person calls, and certain...
s using patch cords
Cord circuit
In telecommunication, a cord circuit is a switchboard circuit in which a plug-terminated cord is used to establish connections manually between user lines or between trunks and user lines. A number of cord circuits are furnished as part of the switchboard position equipment. The cords may be...
to connect one party to another. If a person wanted to make a phone call, in some phone systems he or she would pick up a phone and wind a crank on the side. In other systems the person would wind the crank first, then pick up the phone. The crank was a small generator that would light a lamp at the central office. An operator would see the light and insert their patch cord into a socket and assist the customer with the call connection. The operator would use patch cords to connect the caller to the person being called. If the party being called was in another exchange, the operator would use a patch cord to connect to another exchange where an operator elsewhere would finish the connection. As technology advanced, electro-mechanical switches were introduced and calls were made using rotary dial
Rotary dial
The rotary dial is a device mounted on or in a telephone or switchboard that is designed to send electrical pulses, known as pulse dialing, corresponding to the number dialed. The early form of the rotary dial used lugs on a finger plate instead of holes. Almon Brown Strowger filed the first patent...
s.
Initial use of area codes in the United States and Canada began in the late 1940s with large cities. By 1966, the system was implemented fully in both countries.
Area codes were assigned based on the length of time a rotary dial
Rotary dial
The rotary dial is a device mounted on or in a telephone or switchboard that is designed to send electrical pulses, known as pulse dialing, corresponding to the number dialed. The early form of the rotary dial used lugs on a finger plate instead of holes. Almon Brown Strowger filed the first patent...
phone took to dial the area code. Densely populated areas like New York City, Chicago, Los Angeles, and Detroit had huge incoming call volume and were assigned numbers (212
Area code 212
Area code 212 is a New York City telephone area code for the borough of Manhattan. By area, it is one of the smallest area codes in North America....
, 312
Area code 312
Area code 312 is the telephone area code for the Chicago Loop and surrounding areas of the city of Chicago, Illinois. Prior to the split on November 11, 1989, forming 708 , 312 area code originally served much of Greater Chicago...
, 213
Area code 213
North American area code 213 is a Californian telephone area code which contains downtown Los Angeles and its immediate environs. It was one of California's original three area codes created in October 1947 and has historically been associated with Southern California and Los Angeles.Originally,...
, 313
Area code 313
Area code 313 is the telephone area code serving the city of Detroit, Michigan, the city's innermost enclave cities , and Dearborn, Redford and Grosse Pointe...
) that could be quickly dialed from a rotary dial phone. On a rotary dial phone low digits (1, 2, 3, 4) could dial quickly as the time the rotary dial took to return to the home position was minimal. High digit numbers (7, 8, 9, 0) on rotary dial phones took much longer to return to the home position and were usually used in less densely populated areas like rural Texas (915). This numbering strategy became unnecessary when touch-tone
Dual-tone multi-frequency
Dual-tone multi-frequency signaling is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. The version of DTMF that is used in push-button telephones for tone dialing is...
phones arrived, as the tone allowed instant entry of digits.
The original set of North American area codes was unique. When the North American Numbering Plan
North American Numbering Plan
The North American Numbering Plan is an integrated telephone numbering plan administered by Neustar which encompasses 24 countries and territories, including the United States and its territories, Canada, Bermuda, and 16 nations of the Caribbean...
was first developed, logic circuits consisted of relays and vacuum tubes, and simplicity was mandatory. The second digit of all area codes was 0 or 1, while the second digit of the exchange triplet was never 0 or 1, thus facilitating readily the recognition whether the dialing of a full 10-digit number was in progress or whether the user was dialing only a local number. In this coding scheme, a leading 1 indicating long distance, or out of the area code call, was not necessary. In some regions, local numbers were 7 digits (occasionally less), but a toll call within the area code required a preceding “1”. This told the subscriber that the call being placed was a toll call. Area Code 617 in eastern Massachusetts used this system in the early 1970s, while the Chicago area (Area Code 312) did not. In the Chicago Area, one could call the Boston area by dialing only 10 digits, while in Boston, to call Chicago, one would be required to use 11 digits (preceding the 10 digits with a “1”)
By the 1990s, the mechanical Central Office Switches were rapidly being replaced with ESS machines (Electronic Switching Systems), and the Area Code logic was no longer necessary. The need for more telephone numbers was increasing rapidly, and the NANPA (North American Numbering Plan Administration) was running out of “n0n” and “n1n” combinations. This Area Code scheme was abandoned, with the result that former Area Code only numbers could now be Exchanges, and former Exchange only numbers could now be Area Codes. This caused a logic dilemma: The Switch had no way of knowing whether to expect 10 digits or 7 digits. The solution was simple. If a preceding “1” was entered (by dial and Touch-Tone key pad), then 10 more digits were expected. If the first digit entered was NOT a “1” only 7 digits were expected and the call would remain within area code. For a short while, in some area codes, one could enter the full 11 digits for a call within their own neighborhood or just enter the last 7 digits, and the call would be routed and billed identically.
Currently, because of Area Code overlays, nearly all metropolitan and many rural telephone calls require the full 11 digit entry to complete a telephone call.
Structure
Most telephone numbers belong to the E.164E.164
E.164 is an ITU-T recommendation that defines the international public telecommunication numbering plan used in the PSTN and some other data networks. It also defines the format of telephone numbers. E.164 numbers can have a maximum of fifteen digits and are usually written with a + prefix...
numbering plan, though some PABXs (business telephone systems) have internal extensions.
The E.164
E.164
E.164 is an ITU-T recommendation that defines the international public telecommunication numbering plan used in the PSTN and some other data networks. It also defines the format of telephone numbers. E.164 numbers can have a maximum of fifteen digits and are usually written with a + prefix...
numbering plan for telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
numbers includes:
- Country calling codes
- Regional numbering plans, such as:
- the European Telephony Numbering SpaceEuropean Telephony Numbering SpaceIn the interest in forming a trans-Europe numbering plan as an option for anyone needing multi-national European telephone presence, the ITU allocated country calling code +388 as a subdivided, catch-all container for such services...
- the North American Numbering PlanNorth American Numbering PlanThe North American Numbering Plan is an integrated telephone numbering plan administered by Neustar which encompasses 24 countries and territories, including the United States and its territories, Canada, Bermuda, and 16 nations of the Caribbean...
- the European Telephony Numbering Space
- Various national numbering plans, such as:
- Telephone numbers in the United KingdomTelephone numbers in the United KingdomThe UK telephone numbering plan, also known as the National Telephone Numbering Plan, is the system used for assigning telephone numbers in the United Kingdom and the Crown Dependencies...
- Telephone numbers in the United Kingdom
Apart from the use of numbering plans for telephone numbers, they are also used in routing of SS7 signalling messages as part of the Global Title
Global Title
A Global Title is an address used in the SCCP protocol for routing signaling messages on telecommunications networks. In theory, a global title is a unique address which refers to only one destination, though in practice destinations can change over time....
. In public land mobile network
Public land mobile network
A public land mobile network is a regulatory term in telecommunications. A PLMN is a network that is established and operated by an administration or by a recognized operating agency for the specific purpose of providing land mobile telecommunications services to the public.A PLMN is identified...
s, the E.212 numbering plan is used for subscriber identities (e.g. stored in the GSM SIM
Subscriber Identity Module
A subscriber identity module or subscriber identification module is an integrated circuit that securely stores the International Mobile Subscriber Identity and the related key used to identify and authenticate subscriber on mobile telephony devices .A SIM is held on a removable SIM card, which...
) while E.214
E.214
E.214 is a numbering plan used for delivering mobility management related messages in GSM networks. The E.214 number is derived from the IMSI E.212 numbers are composed of two parts. The first, the E.164 part, is made up of a country code followed by the network code. The second part of the...
is used for routing database queries across PSTN networks.
Country code
Country code - necessary only when dialing to phones in other countries. In international usage, telephone numbers are prepended with the country code preceded by a "+", and with spaces in place of hyphens (e.g., "+XX YYY ZZZ ZZZZ"). This allows the reader to choose which Access Code (also known as International Dialing Digit) they need to dial from their location. However, it is often quoted together with the international access code which must precede it in the dial string, for example "011" in NANP countries (including Canada, Bermuda, and the United States): "011-XX-YYY-ZZZ-ZZZZ", or "00" in most European countries: "00-XX-YYY-ZZZ-ZZZZ". This can cause confusion as a different Access Code may be used where the reader is located. On GSM networks, "+" is an actual character that may be used internally as the international access code, rather than simply being a convention.Area code
Area codes are also known as Numbering Plan Areas (NPAs) and formerly known as STD codesSubscriber trunk dialling
Subscriber trunk dialling is a term for a telephone system allowing subscribers to dial trunk calls without operator assistance.- Terminology :...
in the UK. These are necessary (for the most part) only when dialed from outside the code area, from mobile phones, and (especially within North America) from within overlay plan
Overlay plan
In telephony, especially in North America, an overlay plan is the practice of introducing a new area code by applying it onto a geographic area that is already occupied by one or more existing area codes, resulting in two area codes serving the same area.- Methodology :Prior to the introduction of...
s. Area codes usually indicate geographical areas within one country that are covered by perhaps hundreds of telephone exchanges, although the correlation to geographical area is becoming obsolete.
The area code is usually preceded in the dial string by either the national access code
Trunk prefix
A trunk prefix is the number to be dialed in a domestic telephone call, preceding any necessary area codes and subscriber numbers. When the number is called from overseas, the trunk prefix is omitted by the caller. In most countries, such as Australia, Germany and the United Kingdom, the trunk...
("0" for many countries, "1" in USA and Canada) or the international access code and country code. However, this is not always the case, especially when 10-digit dialing is used. For example, in Montreal, Quebec, where area codes 514 and 450 are currently in use, users dial 10-digit number (ex 514 555 1234), dialing a 1 before this results in a recording advising not to dial a 1 as it is a local call. For non-geographic numbers, as well as mobile telephones outside of the North American Numbering Plan area, the "area code" does not correlate to a particular geographic area.
Area codes are often quoted including the national access code, for example a number in London: 020 8765 4321. Users must then correctly interpret the "020" as the code for London. If calling from another number in London they merely dial 8765 4321, or if dialing from another country, drop the "0" and dial: +44 20 8765 4321.
000 area codes
Area code 000
Area code 000, while not a valid United States area code, is actually an "outbound-only" area code. This code may show up as part of a number on a caller id system when receiving telemarketer outbound calls or from VoIP services, such as Skype or Vonage....
are sometimes used in the United States by telemarketers and VoIP services. They are only used for outgoing calls, and can not be dialed.
Area codes were introduced in the United States by the Bell System
Bell System
The Bell System was the American Bell Telephone Company and then, subsequently, AT&T led system which provided telephone services to much of the United States and Canada from 1877 to 1984, at various times as a monopoly. In 1984, the company was broken up into separate companies, by a U.S...
, in 1947. The first direct dial long distance call
Long Distance Call
"Long Distance Call" is an episode of the American television anthology series The Twilight Zone.-Synopsis:A boy communicates with his father's European-immigrant mother, who had recently died, using a toy telephone that she gave him on his birthday before her passing. The boy, Billy, runs out in...
occurred in 1951.
Local number
The local number (or subscriber number) must always be dialed in its entirety. The first few digits in the local number typically indicate smaller geographical areas or individual telephone exchangeTelephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
s. In mobile networks they may indicate a network provider in case the area code does not. Callers from a number with a given area/country code usually do not need to (but optionally may) include the particular area/country code in the number dialed, which enables shorter "dial strings" to be used. Devices that dial phone numbers automatically can include the full number with area and access codes, since there is no additional annoyance related to dialing extra digits.
Standards
Although the International Telecommunication UnionInternational Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
(ITU) has attempted to promote common standards among nation states, numbering plans take different formats in different parts of the world. For example, the ITU recommends that member states adopt 00 as their international access code. However, as these recommendations are not binding on member states, some have not, such as the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, and other countries and territories participating in the North American Numbering Plan
North American Numbering Plan
The North American Numbering Plan is an integrated telephone numbering plan administered by Neustar which encompasses 24 countries and territories, including the United States and its territories, Canada, Bermuda, and 16 nations of the Caribbean...
.
The international numbering plan establishes country codes, that is, area codes that denote nations or groups of nations. The E.164
E.164
E.164 is an ITU-T recommendation that defines the international public telecommunication numbering plan used in the PSTN and some other data networks. It also defines the format of telephone numbers. E.164 numbers can have a maximum of fifteen digits and are usually written with a + prefix...
standard regulates country code
Country code
Country codes are short alphabetic or numeric geographical codes developed to represent countries and dependent areas, for use in data processing and communications. Several different systems have been developed to do this. The best known of these is ISO 3166-1...
s at the international level and sets a maximum length limit on a full international phone number (15 digits). However, it is each country's responsibility to define the numbering within its own network. As a result, regional area codes may be:
- A fixed length, e.g., three digits in the United StatesCommunications in the United StatesThe primary regulator of communications in the United States is the Federal Communications Commission. It closely regulates all of the industries mentioned below with the exception of newspapers and the Internet service provider industry.- Press :...
and CanadaCommunications in Canada-Telephone:Telephones – main lines in use: 18.251 million Telephones – mobile cellular: 23.081 million Telephone system:* general assessment: excellent service provided by modern technology...
; two digits in BrazilCommunications in BrazilBrazil has both modern technologies in the center-south portion, counting with 3G HSDPA, VDSL2+, Digital TV. Other areas of the country, particularly the north and north-west regions, lack even basic analogue land line phones...
; one digit in AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and New ZealandTelephone numbers in New ZealandCountry calling code: +64International call prefix: 00Trunk prefix: 0The New Zealand telephone numbering plan describes the allocation of telephone numbers in New Zealand.-History:...
, - A variable length, e.g., between 2 and 5 in GermanyTelephone numbers in GermanyCountry Code: +49International Call Prefix: 00Trunk Prefix: 0The German telephone numbering plan is regulated by the German government's Federal Network Agency , which holds the responsibility for telecommunications and other infrastructure systems.- Overview :There are no standard lengths for...
, Argentina, United KingdomTelephone numbers in the United KingdomThe UK telephone numbering plan, also known as the National Telephone Numbering Plan, is the system used for assigning telephone numbers in the United Kingdom and the Crown Dependencies...
and in AustriaAustriaAustria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
; between 1 and 5 in JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
; 1 or 2 in SyriaCommunications in SyriaTelecommunications in Syria is slowly moving towards liberalization, with a number of licenses awarded and services launched in the Internet service provision market. The initiative reflects the government’s change in attitude towards liberalization, following its promise to the European Union to...
and PeruCommunications in PeruThe technical regulator of communications in Peru is the Ministry of Transportation and Telecommunications, through the Organismo Supervisor de la Inversión Privada en Telecomunicaciones .-Telephones:*Main fixed lines in use: 3,413,849 ....
, or - Incorporated into the subscriber's number, as is the case in many countries, such as SpainCommunications in SpainTelephones - main lines in use:18.583 million Telephones - mobile cellular:48.8 million Telephone system:generally adequate, modern facilitiesdomestic:NAinternational:...
or Norway. This is known as a "closed" telephone numbering plan. In some cases a trunk code (usually 0) must still be dialed, as in BelgiumBelgiumBelgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
, ItalyItalyItaly , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
, SwitzerlandSwitzerlandSwitzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
, South AfricaSouth AfricaThe Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
and some locations within the NANPNorth American Numbering PlanThe North American Numbering Plan is an integrated telephone numbering plan administered by Neustar which encompasses 24 countries and territories, including the United States and its territories, Canada, Bermuda, and 16 nations of the Caribbean...
. Hong Kong used to have 1-digit area codes. They were incorporated into the subscriber's numbers back into the 1990s. No trunk code is required.
Area code and call pricing
In countries other than the United States and Canada, the area codes generally determine the cost of a call. Calls within an area code and often a small group of adjacent or overlappingOverlay plan
In telephony, especially in North America, an overlay plan is the practice of introducing a new area code by applying it onto a geographic area that is already occupied by one or more existing area codes, resulting in two area codes serving the same area.- Methodology :Prior to the introduction of...
area codes are normally charged at a lower rate than outside the area code. This is not necessarily the case in the United States or Canada where rates are determined by the distance between rate centers. In most United States and Canadian locations area codes cover a sufficiently large territory that different rates will apply within the same area code determined by the distance between rate centers. Each rate center also has a local calling plan which determines which other rate centers, regardless of distance, are a local call. The area code plus the first three digits following the area code (the NPA-NXX) defines the rate center for any given telephone number. Multiple NPA-NXX combinations, often in different area codes, comprise each rate center, and each rate center is assigned a geographic point known as the rate center's V&H coordinates. The tariff distance in miles between any two rate centers may be calculated using by this formula:
.Calls between nearby rate centers in different area codes may be cheaper (or even free local calls) as compared to calls to more distant rate centers in the same area code. Rates are set in zones of 0-6 mi, 6-12 mi, and so on, with these bands determined on a state-by-state basis for intrastate calls (calls within the same state) and determined by federal regulation for interstate calls (calls which cross a state line). As a specific example, callers in the Falls Church, Virginia, rate center (officially named "Washington Zone 17, VA"--example numbers beginning with 703-534, V=5636, H=1600) may make untimed local calls to 31 other nearby rate centers in Virginia, Maryland, and the District of Columbia in area codes 703, 571, 202, 301, and 240, while calls to distant locations in 703 such as Manassas and Haymarket, VA are charged as long distance.
Calls within a state [regulated by that state's public utilities commission] are often higher than rates to call more distant locations in some other state [regulated by the Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
]. The partial deregulation and introduction of competition for long distance phone services has established other methods of determining call pricing that do not necessarily follow the traditional model. Each year, more customers switch to a fixed rate, "all-you-can-dial" plan covering the state, the United States, or all North America generally (as of May 2008 and exclusive of taxes) for approximately $30 per month. Competition with cable telephony
Cable telephony
Cable telephony is a form of digital telephony over cable TV networks. A telephone interface installed at the customer's premises converts analog signals from the customer's in-home wiring to a digital signal, which is then sent over the cable connection to the company's switching center. The...
and Voice over Internet Protocol services have helped drive the cost of service down for residential and business customers.
Special area codes are generally used for free
Toll-free telephone number
A toll-free, Freecall, Freephone, 800, 0800 or 1-800 number is a special telephone number which is free to the calling party, and instead the telephone carrier charges the called party the cost of the call...
, premium rate
Premium-rate telephone number
Premium-rate telephone numbers are telephone numbers for telephone calls during which certain services are provided, and for which prices higher than normal are charged. Unlike a normal call, part of the call charge is paid to the service provider, thus enabling businesses to be funded via the calls...
, mobile phone
Mobile phone
A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
systems (in countries where the mobile phone system is caller pays) and other special rate numbers. There are however some exceptions, in some countries (like Egypt
Communications in Egypt
Egypt has long been the cultural and informational centre of the Arab world, and Cairo is the region's largest publishing and broadcasting centre.- Press :...
), calls are charged at the same rate regardless of area and in others (like the UK
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
) an area code is occasionally treated as two parts with different rates.
Example
In the U.S.United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, some typical dial plans include:
- Internal extension numbers of a varying number of digits
- Local numbers of seven or ten digits
- Long distance numbers of eleven digits, consisting of a 1, then a three-digit area code, then a seven-digit number
- International numbers of any length starting with 011
Many corporate telephone systems use a dialing prefix, typically the digit 9, to obtain a line to the public switched telephone network.
Example
In AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, the following dialing plans can be found:
- Internal extension numbers of a varying number of digits, usually 3 or 4 digits
- Local numbers of eight digits
- Long distance numbers of eight digits, when source and destination share the same area code, or ten digits, consisting of a 0, then an area code, then eight-digit number
- International numbers of any length starting with 0011
In Australia, the digit 0 is used to obtain a line to the public switched telephone network.
Open dialing plans
An open dialing plan is one in which there are different dialing arrangements for local and long distance telephone calls. This means that to call another number within the same city or area, callers need dial only the number, but for calls outside the area, an area code is required. In this situation it is customary to show the area code in parentheses, signifying that in some cases the area code is optional or is not required, as suggested by ITU-TITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
Recommendation E.123
E.123
E.123, also known as Notation for national and international telephone numbers, e-mail addresses and Web addresses is an ITU-T standard for printed representation of telephone numbers, e-mail addresses, and web addresses.-Example formats:...
. The area code is prefixed by a trunk code (usually "0"), which (apart from rare cases such as Italian land lines) is omitted when calling from outside the country.
To call a number in Sydney, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
for example:
- xxxx xxxx (within SydneySydneySydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
and other locations within New South WalesNew South WalesNew South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
- no area code required) - (02) xxxx xxxx (outside New South WalesNew South WalesNew South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
- the area code is required) - +61 2 xxxx xxxx (outside AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
; notice the dropped 0)
Note that the "+" is not dialed, it signifies that first the international access code must be dialed, followed by the country code, in this case 61, followed by the number. When using a mobile telephone to place a call, all GSM phones and many models using other technologies do allow the + to be entered and this is internally converted to the correct access code, based on caller location, as the call is made.
New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
has a special case of an open dialing plan. While most nations require the area code to be dialed only if it is different, in New Zealand, one needs to dial the area code if the phone is outside the local calling area. For example, the town of Waikouaiti
Waikouaiti
Waikouaiti is a small town in East Otago, New Zealand, within the city limits of Dunedin. The town is close to the coast and the mouth of the Waikouaiti River....
is in the Dunedin
Dunedin
Dunedin is the second-largest city in the South Island of New Zealand, and the principal city of the Otago Region. It is considered to be one of the four main urban centres of New Zealand for historic, cultural, and geographic reasons. Dunedin was the largest city by territorial land area until...
City Council jurisdiction, and has phone numbers (03) 465 7xxx. To call the city council in central Dunedin (03) 477 4000, residents must dial the number in full including the area code even though the area code is the same, as Waikouaiti and Dunedin lie in different local calling areas (Palmerston
Palmerston, New Zealand
The town of Palmerston, in New Zealand's South Island lies 50 kilometres to the north of the city of Dunedin. It is the largest town in the Waihemo Ward of the Waitaki District with a population of 890 residents...
and Dunedin respectively)
In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, and other countries or territories using the North American Numbering Plan
North American Numbering Plan
The North American Numbering Plan is an integrated telephone numbering plan administered by Neustar which encompasses 24 countries and territories, including the United States and its territories, Canada, Bermuda, and 16 nations of the Caribbean...
(NANP), the trunk code is '1', which is also (by coincidence) the country calling code. The same rule also applies in many parts of the NANP, including all areas of Canada that still have an open dialing plan. This is not universal, as there are locations within the United States that allow long distance calls within the same area code to be dialed as seven digits. In Canada, the trunk code (also known as the long distance access code) must also be dialed along with the area code for long distance calls even within the same area code. For example, to call a number in Regina
Regina, Saskatchewan
Regina is the capital city of the Canadian province of Saskatchewan. The city is the second-largest in the province and a cultural and commercial centre for southern Saskatchewan. It is governed by Regina City Council. Regina is the cathedral city of the Roman Catholic and Romanian Orthodox...
:
- xxx xxxx (within ReginaRegina, SaskatchewanRegina is the capital city of the Canadian province of Saskatchewan. The city is the second-largest in the province and a cultural and commercial centre for southern Saskatchewan. It is governed by Regina City Council. Regina is the cathedral city of the Roman Catholic and Romanian Orthodox...
, LumsdenLumsden, Saskatchewan-History:Settlers first arrived in 1881 and the area came to be commonly known as Happy Hollow. When the Qu'Appelle, Long Lake and Saskatchewan Railway came through the community in 1889, the name was changed to Lumsden after Hugh Lumsden, a senior engineer with the railroad.The town has been...
and other local areas) - 1 (306) xxx xxxx (within the 306 area code, but not within the Regina local calling area (e.g., SaskatoonSaskatoonSaskatoon is a city in central Saskatchewan, Canada, on the South Saskatchewan River. Residents of the city of Saskatoon are called Saskatonians. The city is surrounded by the Rural Municipality of Corman Park No. 344....
)) - 1 (306) xxx xxxx (anywhere within the NANP outside the 306 area code)
- +1 (306) xxx xxxx (outside NANP)
To call a number in San Francisco, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
the dialing procedure will vary:
- xxx xxxx (local calls, no area code required)
- 1 (415) xxx xxxx (outside San Francisco, and within the U.S., Canada, and other countries in the NANP)
- +1 (415) xxx xxxx (outside the NANP - 1 is the country code for the U.S.)
However, in parts of North America, especially where a new area code overlays an older area code, dialing the area code, or 1 + the area code, is now required even for local calls, which means that the NANP is now closed in certain areas and open in others. Dialing from mobile phones is different in the U.S., as the trunk code is not necessary, although it is still necessary for calling all long distance numbers from a mobile phone in Canada. (Most mobile phones today can be programmed to automatically add a frequently-called area code as a prefix, allowing calls within the desired area to be dialed by the user as seven-digit numbers, though sent by the phone as 10-digit numbers.)
In some parts of the United States, especially northeastern states such as Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
served by Verizon Communications
Verizon Communications
Verizon Communications Inc. is a global broadband and telecommunications company and a component of the Dow Jones Industrial Average...
, the full 10-digit number must be dialed. If the call is not local, the call will not complete unless the dialed number is preceded by a 1. In this situation, where the area code is not optional, the area code is not enclosed in parentheses. Thus:
- 610 xxx xxxx (local calls, area code required; one of two completion options for mobile phones within the U.S.)
- 1 610 xxx xxxx (intra-area code charged calls; second of two completion options for mobile phones within the U.S.)
- +1 610 xxx xxxx (outside the NANP)
In areas served by AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, pre-recorded messages instruct customers that use of the local area code within the area code is not permissible and that only the xxx xxxx format is permitted.
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. This "feature" is unintentionally helpful for employees who reside in one area code and work in an area code with one, two, or three adjacent area codes. "1+" dialing to any area code by an employee can be done quickly, with all exceptions processed by the private branch exchange and passed onto the public switched telephone network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
.
Open and closed dialing plans should not be confused with open and closed numbering plans. A closed numbering plan, such as found in North America, features fixed length area codes and local numbers. An open numbering plan, as found in assorted countries that have not yet standardized, features variance in length of area code or local number, or both. Closed dialing plans are rare where numbering plans are open.
Closed dialing plans
A closed dialing plan is one in which the subscriber's full number is used for all calls, even in the same area. This has traditionally been the case in small countries and territories where area codes have not been required. However, there has been a trend in many countries towards making all numbers a standard length, and incorporating the area code into the subscriber's number. This usually makes the use of a trunk code obsolete.For example, to call Oslo in Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
before 1992, one would dial:
- xxx xxx (within Oslo - no area code required)
- (02) xxx xxx (within Norway - outside Oslo)
- +47 2 xxx xxx (outside Norway)
After 1992, this changed to a closed eight-digit numbering plan, e.g.:
- 22xx xxxx (within Norway - including Oslo)
- +47 22xx xxxx (outside Norway)
Therefore in other countries, such as France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
and some parts of North America where the dialing plan is closed, the trunk code is retained for domestic calls, whether local or national, e.g.,
- Paris 01 xx xx xx xx (outside France +33 1 xxxx xxxx)
- Brussels 02 xxx xxxx (outside Belgium +32 2 xxx xxxx)
- Geneva 022 xxx xxxx (outside Switzerland +41 22 xxx xxxx)
- Cape TownCape TownCape Town is the second-most populous city in South Africa, and the provincial capital and primate city of the Western Cape. As the seat of the National Parliament, it is also the legislative capital of the country. It forms part of the City of Cape Town metropolitan municipality...
021 xxx xxxx (outside South Africa +27 21 xxx xxxx) - New York 1 212 xxx xxxx (outside the North American Numbering Plan +1 212 xxx xxxx)
while some, like Italy, require the initial zero to be dialled, even for calls from outside the country, e.g.,
- Rome 06 xxxx xxxx (outside Italy +39 06 xxxx xxxx)
Further, there are locations with closed dialing plans in the NANP that require the full phone number including area code to be dialed for all calls, but the trunk code is required for only long distance calls, even in the same area code.
While the use of full national dialing is less user-friendly than using only a local number without the area code, the increased use of mobile phones, which can store numbers, means that this is of decreasing importance. It also makes easier to display numbers in the international format, as no trunk code is required—hence a number in Prague
Prague
Prague is the capital and largest city of the Czech Republic. Situated in the north-west of the country on the Vltava river, the city is home to about 1.3 million people, while its metropolitan area is estimated to have a population of over 2.3 million...
, Czech Republic
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
, can now be displayed as:
- 2xx xxx xxx (inside Czech Republic)
- +420 2xx xxx xxx (outside Czech Republic)
as opposed to before September 21, 2002:
- 02 / xx xx xx xx (inside Czech Republic)
- +420 2 / xx xx xx xx (outside Czech Republic)
Some countries already switched, but trunk prefix re-added with the closed dialing plan, for example in Bangkok, Thailand before 1997:
- xxx-xxxx (inside Bangkok)
- 02-xxx-xxxx (inside Thailand)
- +66 2-xxx-xxxx (outside Thailand)
has been switched in 1997:
- 2-xxx-xxxx (inside Thailand)
- +66 2-xxx-xxxx (outside Thailand)
Trunk prefix has re-added in 2001
- 02-xxx-xxxx (inside Thailand)
- +66 2-xxx-xxxx (outside Thailand)
Satellite phone numbering plans
Satellite phoneSatellite phone
A satellite telephone, satellite phone, or satphone is a type of mobile phone that connects to orbiting satellites instead of terrestrial cell sites...
s are usually issued with numbers in a special country calling code. For example, Inmarsat
Inmarsat
Inmarsat plc is a British satellite telecommunications company, offering global, mobile services. It provides telephony and data services to users worldwide, via portable or mobile terminals which communicate to ground stations through eleven geostationary telecommunications satellites...
satellite phones are issued with code +870, while Global Mobile Satellite System
Global Mobile Satellite System
The Global Mobile Satellite System is a general term referring to the selection of satellite phone providers available to private customers...
providers, such as Iridium, issue numbers in country code +881 ("Global Mobile Satellite System") or +882 ("International Networks"). Some satellite phones are issued with ordinary phone numbers, such as Globalstar
Globalstar
Globalstar is a low Earth orbit satellite constellation for satellite phone and low-speed data communications, somewhat similar to the Iridium satellite constellation and Orbcomm satellite systems.-History:...
satellite phones issued with NANP telephone numbers.
- Inmarsat:+870: SNAC (Single Network Access Code)
- ICO Global: +881 0, +881 1.
- Ellipso: +881 2, +881 3.
- Iridium: +881 6, +881 7.
- GlobalstarGlobalstarGlobalstar is a low Earth orbit satellite constellation for satellite phone and low-speed data communications, somewhat similar to the Iridium satellite constellation and Orbcomm satellite systems.-History:...
: +881 8, +881 9. - Emsat: +882 13.
- ThurayaThurayaThuraya , the Arabic name of the Pleiades, is a regional satellite phone provider. Its coverage area is most of Europe, the Middle East, North, Central and East Africa, Asia and Australia....
: +882 16. - ACeSACeSACeS is a regional satellite telecommunications company based in Jakarta, Indonesia. It offers GSM-like satellite telephony services to Asian market. The coverage area includes Indonesia, Malaysia, Thailand, Philippines, Sri Lanka, Vietnam, China and India. The company operates the Garuda 1...
: +882 20.
Special services
Some country calling codes are issued for special services, or for international/inter regional zones.- +388 5 – shared code for groups of nations
- +388 3 – European Telephony Numbering SpaceEuropean Telephony Numbering SpaceIn the interest in forming a trans-Europe numbering plan as an option for anyone needing multi-national European telephone presence, the ITU allocated country calling code +388 as a subdivided, catch-all container for such services...
– Europe-wide services (discontinued) - +800 – International Freephone (UIFNToll-free telephone numberA toll-free, Freecall, Freephone, 800, 0800 or 1-800 number is a special telephone number which is free to the calling party, and instead the telephone carrier charges the called party the cost of the call...
) - +808 – reserved for Shared Cost ServiceShared Cost ServiceShared Cost Service is an intermediate level of telephone call billing where the charge for calling a particular international phone number is partially, but not entirely, paid for by the recipient. It is also known as ISCS and UISCN...
s - +878 – Universal Personal TelecommunicationsUniversal Personal TelecommunicationsUniversal personal telecommunications is a special segment of the international telephone number space which has been set aside for universal personal telephone numbers. This service has been allocated country code +878. UPT numbers differ significantly from Personal Numbers which are embedded as...
services - +881 – Global Mobile Satellite SystemGlobal Mobile Satellite SystemThe Global Mobile Satellite System is a general term referring to the selection of satellite phone providers available to private customers...
- +882 – International Networks
- +888 - international disaster relief operations
- +979 – International Premium Rate ServiceInternational Premium Rate ServiceInternational premium rate service refers to internationally available telephone-based premium services. It is analogous to "900" or "976" numbers in North America, which always incur a recipient-defined charge in excess of regular call charges. Internationally, this service has been allocated...
- +991 – International Telecommunications Public Correspondence Service trial (ITPCS)
- +996 9 - Kyrgyzstan PG.R.S. Server
- +999 – reserved for future global service
Numbering plans by global regions
- Telephone numbers in the AmericasTelephone numbers in the Americas-North American Numbering Plan:Country Code: +1International Call Prefix: 011Trunk Prefix: 1In the United States , Canada, Bermuda, and 18 Caribbean nations, area codes are regulated by the North American Numbering Plan. Currently, all area codes in the NANP must have 3 digits...
- Telephone numbers in OceaniaTelephone numbers in Oceania-Australia:Country Code: +61International Call Prefix: 0011Trunk Prefix: 0Telephone numbers in Australia consist of a single-digit area code and eight-digit local numbers, the first four, five or six of which specify the exchange, and the remaining four, three or two a line at that exchange...
- Telephone numbers in EuropeTelephone numbers in EuropeMost country calling codes for the European Union countries start with +3x or +4x. The international access code has been standardised as 00.Some countries that are considered by Copenhagen criteria part of Europe use numbers outside that range, namely the Asia range +9:*+90 – Turkey*+994...
- Telephone numbers in AsiaTelephone numbers in Asia-States and territories with country calling codes:-States and territories without a country calling code:-See also:*Telephone numbering plan*List of country calling codes*List of international call prefixes*:Category:Telephone numbers by country...
- Telephone numbers in AfricaTelephone numbers in Africa-States and territories with country calling codes:-States and territories without a country calling code:-See also:*Telephone numbering plan*List of country calling codes*List of international call prefixes*:Category:Telephone numbers by country...
Dial plan syntax
The following syntax used to identify a dial plan in a digit map is adapted from [RFC 2705].{| width="75%" cell spacing="1" cell padding="1" style="background-color: #efefef; border: solid 1px #eeeeee;"
|+ Dial Plan Syntax
|-
!
To specify a
!
Enter the following
!
Result
|-
| Digit
|
| Identifies a specific digit (do not use #)
|-
| Range
|
| Identifies any digit dialed that is included in the range
|-
| Range
|
| Specifies a range as a comma separated list
|-
| Wild card
|
| x matches any single digit that is dialed
|-
| Wild card
|
| . matches an arbitrary number of digits
|-
| Timer
|
| Indicates that an additional time out period of 4 seconds should take place before automatic dialing starts
|-
|}
Some dial plan examples using the above syntax look as follows:
{| width="75%" cellspacing="1" cellpadding="1" style="background-color: #efefef; border: solid 1px #eeeeee;"
|+ Dial Plan Syntax Examples
|-
!
For calls to
!
Users dial
!
Dial plan
|-
| Internal Extension
|
| xx
|-
| Local Number
|
| 9xxxxxxxT
|-
| Emergency
|
| 911
|-
| Local Operators
|
| 90T
|-
| Long Distance
|
| 91xxxxxxxxxx
|-
| International
|
| 9011x.T
|-
|}
Numbering Plan Indicator
The Numbering Plan Indicator (NPI) is a number which is defined in the ITU standard Q.713, paragraph 3.4.2.3.3, indicating the numbering plan of the attached telephone number. NPIs can be found in SCCP and SMSShort message service
Short Message Service is a text messaging service component of phone, web, or mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line or mobile phone devices...
messages. the following numbering plans and their respective Numbering Plan Indicator values have been defined:
| NPI | Description | Standard |
|---|---|---|
| 0 | unknown | |
| 1 | ISDN Telephony | E.164 E.164 E.164 is an ITU-T recommendation that defines the international public telecommunication numbering plan used in the PSTN and some other data networks. It also defines the format of telephone numbers. E.164 numbers can have a maximum of fifteen digits and are usually written with a + prefix... |
| 2 | generic | |
| 3 | data | X.121 X.121 X.121 is the ITU-T address format of the X.25 protocol suite used as part of call setup to establish a switched virtual circuit between Public Data Networks , connecting two network user addresses... |
| 4 | telex Telex Telex may refer to:* Telex , , a communications network** Teleprinter, the device used on the above network* Telex , a Belgian pop group... |
F69 |
| 5 | maritime mobile | E.210 and E.211 |
| 6 | land mobile | E.212 International Mobile Subscriber Identity An International Mobile Subscriber Identity or IMSI is a unique identification associated with all GSM and UMTS network mobile phone users. It is stored as a 64 bit field in the SIM inside the phone and is sent by the phone to the network... |
| 7 | ISDN/mobile | E.214 E.214 E.214 is a numbering plan used for delivering mobility management related messages in GSM networks. The E.214 number is derived from the IMSI E.212 numbers are composed of two parts. The first, the E.164 part, is made up of a country code followed by the network code. The second part of the... |
See also
- List of North American Numbering Plan area codes for the U.S., Canada, Caribbean, and Pacific Ocean islands
- List of United Kingdom dialling codes
- Telephone numbers in Australia
- Carrier access code
External links
- http://www.itu.int/dms_pub/itu-t/opb/sp/T-SP-LT.1-2011-PDF-E.pdf
- List of ITU-T Recommendation E.164 assigned country codes as of 1 Nov 2011
- List of ITU-T Recommendation E.164 Dialling Procedures as of 1 March 2010
- World Telephone Numbering Guide