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A trunk prefix is a digit sequence to be dialed before a telephone number to initiate a telephone call for the purpose of selecting an appropriate telecommunications circuit by which the call is to be routed.
Making a domestic (national) telephone call usually requires the dialing of a single or two-digit national trunk prefix preceding any area codes and the destination subscriber number. In most countries, such as Australia, China, India, France, Germany, Indonesia, Japan, the Netherlands, Sweden, and the United Kingdom, the trunk prefix is 0.
For international telephone calls, the national trunk prefix is not dialed; instead, an international trunk prefix (or "+") is typically required, followed by the destination's country code.
Assume that a call is to be made to a customer in the Australian Area/State of Queensland with the local number of 3333 3333 and the area code 7.
A caller from outside Australia must dial the international call prefix of the originating country, plus the country calling code (61 in the case of Australia), plus the area code (7 in this case), and then the local subscriber number. Therefore, a caller in the UK must dial 00 61 7 3333 3333, while a caller in the US must dial 011 61 7 3333 3333.
Calling inter-area (within Australia) (e.g. from Western Australia—area code 8), a caller need not dial an international trunk prefix or a country code. However, the caller must at least dial the Australian trunk prefix (0) followed by the area code (7) and then the local subscriber number: 07 3333 3333. Calling from within the Queensland (7) area, a caller need only dial the telephone number: 3333 3333.
However, since the early 21st century, the majority of telephone systems worldwide are able to recognize the area of origin of the call, its direction and destination in order to facilitate communication faster. If the full international number is used, then this full international number may be dialed from nearly any telephone within a recognizable landline or mobile network. This has become particularly vital for users of mobile phones.
When conducting business, e.g., for display on business cards or stationery, the number would be +61 7 3333 3333 instead, and include only the digits that must be dialed from internationally. The plus sign is used to indicate that an international trunk prefix is first dialed and, therefore, a country code then follows. It has become common (but incorrect) practice to write the number with the national trunk prefix in parentheses,for example: +61 (0) 7 3333 3333. However, someone calling this number from the U.S. may mistake the national trunk code for a single-digit area code, as NANP area codes are often written in parentheses, dial all the digits and result in a misdirected or failed call. ITU-T Recommendation E.123 states that parentheses should not be used in the international notation to avoid such confusion.
The number next to the country in the list below denotes the country's national trunk prefix.
The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the international calling code 1. Some North American countries, most notably Mexico, do not participate in the NANP.
A toll-free telephone number or freephone number is a telephone number that is billed for all arriving calls instead of incurring charges to the originating telephone subscriber. For the calling party, a call to a toll-free number from a landline is free of charge.
A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks.
Telephone numbers in the United Kingdom are administered by the Office of Communications (Ofcom). For this purpose, Ofcom established a telephone numbering plan, known as the National Telephone Numbering Plan, which is the system for assigning telephone numbers to subscriber stations.
The Australian telephone numbering plan describes the allocation of phone numbers in Australia. It has changed many times, the most recent major reorganisation by the Australian Communications and Media Authority taking place between 1994 and 1998.
In telecommunications, a long-distance call (U.S.) or trunk call is a telephone call made to a location outside a defined local calling area. Long-distance calls are typically charged a higher billing rate than local calls. The term is not necessarily synonymous with placing calls to another telephone area code.
In Argentina, area codes are two, three, or four digits long. Local customer numbers are six to eight figures long. The total number of digits is ten, for example, phone number (11) 1234-5678 for Buenos Aires is made up of a 2-digit area code number and an 8-digit subscriber's number, while (383) 123-4567 would be an example of a Catamarca number.
Numbers on the Irish telephone numbering plan are regulated and assigned to operators by ComReg.
Telephone numbers in Cyprus follow a closed telephone numbering plan which was adopted on 1 December 2001. As a result, for landline phone numbers the digit 2 followed by the old area code was affixed to the subscriber number and for mobile phones 9 was affixed to the phone number. The plan is also used in Akrotiri and Dhekelia.
Area code 246 is the telephone area code in the North American Numbering Plan (NANP) for Barbados. Telecommunication services in Barbados are regulated by the Government of Barbados's telecommunications unit. The number 246 spells BIM on an alpha-numeric telephone keypad, a nickname for the island.
Widespread UK telephone code misconceptions, in particular brought on by the Big Number Change in 2000, have been reported by regulator Ofcom since publication of a report it commissioned in 2004.
The dialling plan for mobile networks and new landline operators is closed; all subscriber numbers must be dialled in full. For landline numbers starting with 02, the dialling plan used to be open; the trunk digit and area code could be omitted if the caller was in the same area code as the callee. However, starting May 3, 2008, all landline numbers must be dialled in full.
The Brazilian telephone numbering plan uses a two-digit area code plus eight-digit local phone numbers for landlines and nine digits for mobile lines. Public utility services use short phone numbers, always starting with 1.
The New Zealand telephone numbering plan describes the allocation of telephone numbers in New Zealand and the Pitcairn Islands.
Telephone numbers in Italy are managed by the Autorità per le Garanzie nelle Comunicazioni (AGCOM), a national regulatory authority for the communication industry located in Rome.
A telephone number in Belgium is a sequence of nine or ten digits dialed on a telephone to make a call on the Belgian telephone network. Belgium is under a full number dialing plan, meaning that the full national number must be dialed for all calls, while it retains the trunk code, '0', for all national dialling.
The national conventions for writing telephone numbers vary by country. While international standards exist in the form of the International Telecommunication Union sector ITU-T issued recommendation E.123, national telephone numbering plans define the format and length of telephone numbers assigned to telephones.
A telephone number is a sequence of digits assigned to a fixed-line telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices for data transmission via the public switched telephone network (PSTN) or other public and private networks.