A telephone number is a sequence of decimal digits (0-9) that is used for identifying a destination telephone line in a telephone network. Telephone numbers are often assigned to lines that have other devices hooked to them such as faxes, modems, subscribers and network services. Each such endpoint must have a unique number within the public switched telephone network, and the number of endpoints determine the necessary length of the telephone number. It is also possible for each subscriber to have a set of shorter numbers for the endpoints most often used. These "shorthand" numbers are automatically translated to unique telephone numbers before the call can be connected. Some special services have their own short numbers (e.g. 9-1-1 and 4-1-1).
Most telephone networks nowadays are interconnected in the international telephone network, where the format of telephone numbers is standardized by ITU-T in the recommendation E.164, which specifies that the entire number should be 20 digits or shorter, and begin with a country prefix. In most countries, this is followed by an area code or city code and the subscriber number, which might consist of the code for a particular telephone switch. ITU-T recommendation E.123 describes how to represent an international telephone number in writing or print, starting with a plus sign ("+") and the country code.
Before a telephone call is connected, the telephone number must be dialed by the calling party or caller. The called party might have equipment that presents caller ID before the call is answered.
History
After Alexander Graham Bell invented the telephone in 1876, it was soon used as a subscription service with the invention of the telephone switch or central office. Such an office was manned by an operator that connected the calls by personal names.
The latter part of 1879 and the early part of 1880 saw the first use of telephone numbers at Lowell, Massachusetts. During an epidemic of measles, Dr. Moses Greeley Parker feared that Lowell's four telephone operators might succumb and bring about a paralysis of telephone service. He recommended the use of numbers for calling Lowell's more than 200 subscribers so that substitute operators might be more easily trained in the event of such an emergency. Parker was convinced of the telephone's potential, began buying stock, and by 1883 he was one of the largest individual stockholders in both the American Telephone Company and the New England Telephone and Telegraph Company.
Even after the assignment of numbers, operators still connected most calls into the early 20th century; "Hello, central, get me UNderwood-342"
Connecting through operators or "central" was usual until mechanical dialing of numbers became more common in the 1920s.
In North America, digits of phone numbers were alloted 3 or 4 letters of the alphabet.
Phone numbers were not usually strictly numeric until the 1950s. From the 1920s until then, most urban areas had "exchanges" of two letters, followed by numbers. This was considered easier to remember, although in the later part of this period it required the memorization of 7 characters (the same number of characters as is usual for local calling in 2003). A word would represent the first two digits to be dialed, for example "TWinbrook" for "89" ; "BYwater" for "29"; 736-5000 was "PEnnsylvania - 6- 5 thousand". These exchanges would be left off for calling people within one's neighborhood, but needed to be included for calls of any greater distance.
Phone numbers were traditionally tied down to a single location, but the introduction of mobile telephones has changed this. In many countries, the practice of number portability allows customers to transfer a phone number from one local exchange company to another, or even from a fixed-line phone to a mobile phone.
An 'open' numbering plan is one in which there are different dialing arrangements for local and long distance telephone calls. This means that to call another number withn the same city or area, callers need only dial the number, but for calls outside the area, an area code is required. The area code is prefixed by a trunk code (usually '0'), which is omitted when calling from outside the country. To call a number in Amsterdam in the Netherlands for example:
Open Numbering Plans
xxx xxxx (within Amsterdam- no area code required)
(020) xxx xxxx (outside Amsterdam)
+31 20 xxx xxxx (outside the Netherlands)
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 the country calling code. To call a number in
xxx xxxx (inside San Francisco - no area code required) 1 415 xxx xxx (outside San Francisco) +1 415 xxx xxxx (outside NANP)
Closed Numbering Plans
A 'closed' numbering plan is one in which the subscriber's number is a standard length, and 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 before 1992, one would dial:
xxx xxx (within Oslo - no area code required) (02) xxx xxx +47 2 xxx xxx (outside Norway)After 1992, this changed to a closed eight-digit numbering plan, eg:
22xx xxxx (within Norway - including Oslo) +47 22xx xxxx (outside Norway)In other countries, such as France, Belgium, Switzerland, and South Africa, the trunk code is retained for domestic calls, whether local or national, eg:
Paris 01 xxxx xxxx (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 Town 021 xxx xxxx (outside South Africa +27 21 xxx xxxx)While the use of full national dialing is less user-friendly than only using a local number without the area code, the increased use of mobile phones, which require full national dialing and 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:
+420 2 xxxx xxxx formerly: 02 xxxx xxxx (inside Czech Republic) +420 2 xxxx xxxx (outside Czech Republic)
North America
The United States (including most of its Dependent Areas), Canada, and several countries in the Caribbean share a common telephone numbering format using the North American Numbering Plan (NANP), originally administered by Bellcore but now by the North American Numbering Plan Administrator (www.nanpa.com).
However, calls between different countries and territories that use the NANP are not charged as domestic. Calls between the US and Canada are generally treated as international, although charged at much lower rates than calls to other countries. Call costs to other destinations in the NANP area can be even higher- for example, it costs more to call Bermuda from the US than it does to call the UK or Japan, even though the dialing format is the same. Similarly, calls from Bermuda to US numbers, (including toll-free 1-800), incur (high) international rates.
A telephone number in the NANP, consists of three parts. An example might be 303-555-1212. The area code or NPA (Numbering Plan Area) is a three digit number (the 303 above) which allows the system to route calls into a small geographic area.
Within each area code are individual exchange numbers, represented by the second three digits, 555 in the above example. This usually represents a specific central office switching machine (or telephone switch). This local machine may actually operate with several exchange numbers, such as 555, 554, 553 and 552 (the numbers need not, however, be consecutive). Exchange numbers are also known as NXXs - not an abbreviation but a code where N=2..9 and X=0..9.
The final four digits are the subscriber number or line number, 1212 in the example above. This number connects to a specific telephone circuit within the exchange.
It is traditional in American television and film to have all fictitious phone numbers begin with 555, as in 555-3245 (also known as KLondike-5 in older movies). This exchange number is typically unused by phone companies, avoiding innocent people being bombarded with unwanted phone calls. An exception is the number 555-1212 which is directory service in the US for each area code, it is basically the 411 service outside the local area code. Some regional services such as Pacific Bell (now SBC Communications) in California are now (as of 2001) converted to provide nationwide directory service via the 411 numbers which makes the (???) 555-1212 number unnecessary within California.
Some common special numbers in the North American system:
0 - operator assist 00 - Long Distance Operator Assist 011 - International access code (for all destinations outside NANP) 10 - used to indicate use of an alternative long distance service 311 - non-emergency police matters (in some cities) 411 - local directory service 511 - traffic, road, and tourist information (in some cities and states) 611 - telephone line repair service 711 - relay service for hearing-impaired or mute customers 911 - emergency dispatcher for fire, ambulance, police etc.Not all countries use the same numbering system. The emergency telephone number is often different from country to country.(area code) 555-1212 - non-local directory service.
There are also special codes, such as:
*70 Cancel call waiting *67 Caller ID Block *69 Call Return caller may press '1' to return call after hearing number *82 releases Caller ID on a call-by-call basisUntil 1995, the second digit of NPA codes was either '0' (e.g: Washington DC 202) or '1' (e.g: Manhattan 212), but this requirement ended, so as to create new codes. Countries and territories in the Caribbean using the NANP had previously shared the NPA code 809, but this was replaced by new codes.
- Bermuda
Until 1995: +1 809 29x xxxx After 1995: +1 441 xxx xxxxThe NPA code 809 is now only used by the Dominican Republic. In 1997 the US Pacific Territories), of the Northern Marianas and Guam became part of the NANP, thereby being rated as domestic long distance from the US: (American Samoa is to follow suit in 2004.)
- Northern Marianas
Until 1997: +670 xxx xxxx After 1997: +1 670 xxx xxxx
- Guam
Until 1997: +671 xxx xxxx After 1997: +1 671 xxx xxxx
- American Samoa
Until 2004: +684 xxx xxxx After 2004: +1 684 xxx xxxxThe increased availability of new NPA codes has also meant that many cities in the US and Canada now have more than one area code, in what is called an 'overlay' scheme. For example in Manhattan, New York, subscribers' numbers had the NPA code 212, but two additional codes--first 917, then 646--were also introduced. This means that the area code must be dialed, even for local calls. In other areas, 10-digit or 11-digit dialing is now required for all local calls.
7-digit dialing: xxx xxxx (NPA code not required) 10-digit dialing: NPA xxx xxxx 11-digit dialing: 1 NPA xxx xxxsee also country calling codes, ANAC
Russia and Commonwealth of Independent States
Under the Russian numbering plan, the trunk code is '8', with subscribers numbers being a total of ten digits long, e.g Moscow:
xxx xxxx (within Moscow) 8 095 xxx xxxx (within Russia and some CIS republics) +7 095 xxx xxxx (outside Russia and some CIS republics)Following the break-up of the former Soviet Union, all former republics apart from Kazakhstan now have separate international from Russia, although from some republics, the old area codes are still used. The international access code is 8~10 - callers dial '8', wait for a tone, and then dial '10', followed by the number.
The telephone service in the United Kingdom was originally provided by local city councils, until in 1912 all except the telephone service of Kingston-upon-Hull, Yorkshire, were bought out by the Post Office. Post Office Telephones also operated telephone services in the Channel Islands (Jersey and Guernsey), and the Isle of Man, until 1969], when the Islands took over responsibility for their own postal and telephone services.
Post Office Telephones was reorganised in the early 1970s as British Telecommunications (British Telecom, or BT), and was one of the first nationalised industries to be privatised by the Conservative government in the mid-1980s. The Hull Telephone Department was itself sold by Hull City Council as Kingston Communications in the late 1990s.
Telephone services in the UK are regulated by the Office of the Telecommunications(Oftel), to be replaced by the Office of Communications (Ofcom) in 2003.
The use of alphabetic exchange (area) codes was abandoned in the 1960s.
The leading '0' of an area code is called the trunk code. All calls within the same area code and geographically adjacent codes are local calls, more distant calls are charged at the national rate. London formed one large area code (01) until 1990, when it was split into two areas 071 being for inner London (later 0171) and 081 for outer London (later (0181). In 2000, this changed to a new single area code (020) with eight-digit numbers, but many people still give out numbers as '0207' (for inner london) and '0208' (for outer London), as the code for central London was considered more prestigious.
The national emergency services call number is 999, although the international number 112 is also recognised.
The operator is obtained via 100, while directory enquiries, formerly 192 is now provided by different companies in the 118xxx range e.g. 118500, 11 88 88. The international access code is 00, which changed from 010 on April 16, 1995, known as 'PhONE Day'.
On 'PhONE Day', the digit '1' was inserted into area codes, with a view to reorganising the numbering plan, so that the first two digits would indicate the type of service called:
United Kingdom
01 Geographic area codes
02 New geographic area codes
03 Geographic area code expansion
04 Reserved for future use
05 Corporate numbering (not yet in use)
06 Corporate numbering expansion
07 Mobile phones, pagers and personal numbering
08 Freephone and shared cost
09 Premium rate- similar to US 1 900 number range
Following the changes in 1995, 2000 and 2001, the numbering range in use is as follows:
- 01xxx xxxxxx - the commonest geographical number format, a five digit area code and six digit subscriber number, e.g:
01382 Dundee 01482 Hull 01582 LutonThe Channel Islands and the Isle of Man continue to participate
in the UK's National Numbering Plan (NNP), using the following area codes:
01481 Guernsey 01534 Jersey 01624 Isle of Man
- 01x1 xxx xxxx - the geographical number format for the larger cities, a four digit area code, with a seven digit subscriber number where the first three digits identifies an area within the city.
0121 Birmingham 0131 Edinburgh 0141 Glasgow 0151 Liverpool 0161 Manchester 0171 used for inner London until 2000 0181 used for outer London until 2000 0191 Newcastle upon Tyne
- 011x xxxxxxx - the geographical number format for a second tier of large cities, a four digit area code, with a seven digit subscriber number, e.g:
0113 Leeds 0114 Sheffield 0115 Nottingham 0116 Leicester 0117 Bristol 0118 Reading
- 02x xxxx xxxx - a new geographical number format with an 8-digit subscriber number, introduced for areas which had run out of spare numbers using six or seven digit numbers, e.g:
020 London 023 Southampton (023 80xx xxxx) and Portsmouth (023 80xx xxxx) 024 Coventry 028 Northern Ireland (Belfast 028 90xx xxxx, Derry 028 71xx xxxx) 029 Cardiff (may become code for Wales)
- 05x xxxx xxxx - reserved for corporate numbering.
055 xxxx xxxx to be introduced by BT.
- 07xxx xxxxxx - mobile phones, pagers and personal numbering. Individual mobile phone companies are allocated different ranges within the 077xx, 078xx and 079xx area codes.
070xx personal numbering 076xx pagers 077xx mobile phone 078xx mobile phone 079xx mobile phone
- 08xx or 08xxx -- non-geographic fixed-rate, or special rate services, e.g.
0800 xxx xxxx or 0800 xxx xxx free phone 0845 xxx xxxx or 08457 xxx xxx local rate 0870 xxx xxxx national rate 0871 xxx xxxx higher national rate
- 09xxx xxxxxx - Premium rate services (no maximum call rate).
141 Number Withhold '1470 Number Release (when permanently withheld) '1471 Call Return (caller may press '3' to return call on hearing number)
Ireland
Telephone numbers in Ireland are similar in format to those in the United Kingdom, with only the subscriber's number being required for local dialing. The trunk prefix is '0' followed by an area code, the first digit indicating the geographical area.
01 Dublin 02 Cork (021) and South 04 Drogheda (041) and East 05 Waterford (051) and South East 06 Limerick (061) and South West 07 Sligo (071)and North West 09 Galway (091) and WestArea codes have varied in length, between one and three digits, and subscribers' numbers between five and seven digits but there is now a migration to a standard format, as follows:
(0xx) xxx xxxxDublin numbers are seven digits, but may change to eight digits in the future. The 08 numbering range was originally used for calls to Northern Ireland, but following the UK's renumbering of Northern Ireland in 2000, this changed, so to call a number in Belfast from the Republic:
Before 2000: (080) 1232 xxx xxx After 2000: (048) 91 xxx xxx; or via the UK numbering plan; 00 44 28 91 xxx xxxThe 03 numbering range was originally used for calls to Britain, but this was discontinued in 1992, when the international access code changed from 16 to 00.
Before 1992: 030 xxx xxx xxx After 1992: 00 44 xxx xxx xxxSimilarly, calls from the UK to Dublin were dialled as 0001 + number, but now the international format (00 353 1 + number is used).
Mobile phones use the prefixes 086, 087 and 088, with 0818 being used for 'find me anywhere' services. Freephone services use the prefix 1800, while shared cost or Lo-Call numbers use the prefix 1850. Internet access numbers use the prefix 1891, 1892 and 1893.
In the late 1980s, France changed to a closed numbering scheme, with the area code being incorporated into the subscriber's eight-digit number. To call the rest of France from Paris, however, the prefix 16 had to be dialled before the eight-digit number, and to call Paris from the rest of France, the prefix 16 1 had to be dialed.
In 1996, this changed to a ten-digit numbering scheme, with Paris numbers prefixed with 01 and areas outside Paris being allocated the prefixes 02, 03, 04 and 05. Mobile phone services were prefixed with 06, and 08 was used for freephone (numero vert) and shared cost services. The international access code also changed from 19 to 00. Following liberalisation in 1998, subscribers could access different carriers by replacing the '0' (omitted from numbers when called from outside France) with another digit, for example Cegetel, required subscribers to dial '7', e.g: Paris 71 xx xx xx xx, instead of 01 xx xx xx xx. Similarly, the international access code using Cegetel would be '70', instead of '00'.)
Until 1996, Monaco formed part of the French numbering plan, with eight-digit numbers beginning with 93, but in that year the Principality adopted the country code 377. Consequently, all calls from France to Monaco must be dialed in international format 00 377 xx xx xx xx, while calls from Monaco to neighboring areas in France similarly must be dialed as 00 33 4 xx xx xx xx. In 1994, Andorra adopted its own country code 376, replacing access via the French numbering plan (+33 628 xxxxx).
The French overseas departments (départements d'outre mer or DOMs), Guadeloupe, Martinique, French Guiana and Réunion have separate country codes from metropolitan France, although they are treated as part of the French numbering plan, with direct dialing for calls between the DOMs (including collectivités territoriales) and metropolitan France.
Since 2001, telephone numbers in the DOMs have folllowed the same ten-digit format as metropolitan France, with the country code being used as a geographical area code, e.g:
French Guiana
Fixed phone line: +594 (0)594 xxx xxx
Mobile phone line: 594 (0)694 xxx xxx
Martinique
Fixed phone line: +598 (0)598 xxx xxx
Mobile phone line: +598 (0)698 xxx xxx
Réunion
Fixed phone line: +262 (0)262 xxx xxx
Mobile phone line: +262 (0)662 xxx xxx
France
Guadeloupe
Fixed phone line: +590 (0)590 xxx xxx
Mobile phone line: +590 (0)690 xxx xxx
Calls between the DOMs and metropolitan France require only the '0' to be dialed. Calls to the collectivités territoriales of Mayotte and Saint Pierre and Miquelon require '0', country code and the subscriber's six-digit number for , eg:
Mayotte 0269 xxx xxxCalls to and from the territoires d'outre mer, however, require full international dialing, hence the international access code and country code must be usedSaint Pierre and Miquelon 0508 xxx xxx
Paris from New Caledonia: 00 33 1 xx xx xx xx, New Caledonia from Paris: 00 687 xxx xxx
Spain
Spain changed to a closed numbering plan in 1998. Previously, the trunk prefix was '9', but this was incorporated into the subscriber's number, so that a nine-digit number was used for all calls, eg:
xxx xxxx (within Madrid) (91) xxx xxxx (within Spain) +34 1 xxx xxxx (outside Spain) +34 91x xxx xxx (after 1998)Mobiles similarly changed, prefixed with the digit '6':
906 xxx xxx (within Spain) +34 06 xxx xxx (outside Spain) +34 606 xxx xxx (after 1998)Spain's international access code also changed from 07 to 00, but this did not affect dialing arangements for calls to Gibraltar, in which the provincial code 9567 is used instead of the international code 350, eg:
9567 xxxxx (Gibraltar from Spain) +350 xxxxx (Gibraltar from all other countries) +34 9567 xxxxx (Gibraltar via Spain)
Italy
Italy changed to achanged to a closed closed numbering plan in 1998, but the trunk code '0' was incorporated into subscribers' landline numbers, e.g a number in Rome:
xxx xxxx (within Rome) (06) xxx xxxx (within Italy) +39 6 xxx xxxx (outside Italy) +39 06 xxx xxx (after 1998)Calls to mobiles were unaffected, with overeas callers continuing to omit the '0':
0333 xxx xxx (within Italy) +39 333 xxx xxx (outside Italy)Until 1996, San Marino was part of the Italian numbering plan, using the Italian area code 0549 but in that year it adopted its own international code 378. However,instead of using international dialing codes, dialling arrangements between San Marino and Italy continued as before. In 1998, San Marino incorporated the 0549 area code into its subscribers' numbers, following the Italian format:
0549 xxx xxx (San Marino from Italy) +378 0549 xxx xxx (San Marino from rest of the world) +39 0549 xxx xxx (San Marino via Italy)
Australia
Telephone numbers in Australia consist of a single digit area code and eight-digit local numbers, the first four of which generally specify the exchange, and the final four a line at that exchange. (Most exchanges though have several four-digit exchange codes.)The long distance prefix is '0', while the main international prefix is '0011' (there are others for special purposes, such as 0018, for charging in half-hour blocks, 0015, for fax traffic, and 0014, for discounted rates).
Australia is divided geographically into a few large area codes, some of which covering more than one state and territory. Prior to the introduction of eight-digit numbers in the early to mid-1990s, telephone numbers were seven digits in the major capital cities, with a single digit area code, and five digits in other areas with a two digit area code.
02 New South Wales and Australian Capital Territory 03 Victoria and Tasmania 07 Queensland 08 Western Australia (including Christmas Island and Cocos Keeling Islands*), South Australia and Northern Territory.)*Until 1994, these territories were not part of the Australian numbering plan, and instead used the code 672, for the Australian External Territories of Norfolk Island and the Australian Antarctic Territory.
Australia also uses the free call area code 1800. This is copied from the U.S. prefix 1-800, but while in North America, the '1' is the long-distance prefix and '800' is the area code, '1800' in Australia is itself an area code (prior to the introduction of 8-digit numbers, the area code was '008'). Similarly, '190x' is the code for charging services (i.e. recorded information, competition lines, psychics, phone sex, etc). (Prior to the introduction of 8-digit numbers, the area code was '0055'.) There are also '13' numbers, which work across large areas (up to across Australia) and only charge a local call, routing the call to the appropriate place in a given area. (For example, a company could have the number 139999 and have the telephone company set it up so that calls made in Melbourne would route to their Melbourne number, calls made in Brisbane to their Brisbane number, and calls made anywhere else in Australia route to their Sydney number, all at a local charge cost to the caller.)
Mobile phone numbers are prefixed with 04, followed by two digits and the subscriber's number, dialled in full, e.g. 0412 xxx xxx. The codes are allocated per network, although with the introduction of number portability there is no longer a fixed relationship between the area code a mobile is in and the network it is attached to.
000 is the emergency telephone number in Australia, but the internationally accepted GSM mobile emergency telephone number 112 also works on mobile phones.
Phone numbers within Australia are allocated by the Australian Communications Authority.
