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A linked numbering scheme (LNS) is a dialing procedure in effect in a service area within which call routing between adjacent exchanges does not require a dialing code.[ citation needed ] The term is only used in the United Kingdom, but not in the North American Numbering Plan.[ citation needed ]
The largest linked numbering scheme in the UK [1] is that for the London telephone area, formerly known as the London Director area. Within the area, several million subscribers can call each other by dialing a uniform code. For example, anyone calling from an (020) number can reach Transport for London travel enquiries by dialing 7222 1234.
Smaller schemes apply outside London. Uxbridge, for example, has the subscriber trunk dialing (STD) code 01895. Uxbridge exchange is the parent for Denham, Harefield, Ruislip and West Drayton; anyone connected to any of those exchanges can call any of the others without having to prefix the number with 01895. This is achieved by giving subscriber lines on each exchange different prefix numbers, thus: all numbers are six-figure; Denham numbers start with 83, Harefield with 82, Ruislip with 6 and West Drayton with 4. Uxbridge numbers start with 2 or 81. All calls must have all six digits dialled - even if a subscriber is on Denham exchange and is calling another subscriber on Denham exchange, they must still dial 83xxxx.
Incoming calls from any other exchange for a subscriber on any of the five exchanges must all be prefixed with the same 01895 code.
The terminology linked numbering scheme is not used in the North American Numbering Plan (NANP).
A local call in this scheme, standardized in 1948 for the introduction of direct-dial long-distance calling, was originally dialled as a fixed-length seven-digit number and did not require an area code. In some cases, a local call to a number just across an area code boundary could be seven digits if an exchange code protection scheme prevented the same prefixes being assigned to local numbers in the other area code.
A long-distance trunk call within the same area code used to be dialable as 1 followed by seven digits, without the area code. This no longer possible everywhere in the NANP by 1995. In areas using toll alerting, where long-distance calls are identified by a trunk prefix (a leading 1-) to be distinguishable from flat-rate local calls, all toll calls must be dialled with the area code.
Some local calls require ten-digit dialling, either across area code boundaries in a split plan or within the same community in an overlay plan. This may mean that no standard numbers are reachable without dialling an area code in some localities.
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.
Subscriber trunk dialling (STD), also known as subscriber toll dialing, is a telephone numbering plan feature and telecommunications technology for the dialling of trunk calls by telephone subscribers without the assistance from switchboard operators.
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.
Seven-digit dialing is a telephone dialing procedure customary in the territories of the North American Numbering Plan, for dialing telephone numbers in the local calling area. These telephone numbers consist of ten digits in full — three for the regional "area code", three for a more local "central office code", and four for the specific telephone — and seven-digit dialing is the ability to dial a number without using the area code. The procedure is also sometimes known as local format or network format.
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.
Number pooling is a method of reallocating telephony numbering space in the North American Numbering Plan, primarily in growth areas in the United States.
The area code 868 is assigned to Trinidad and Tobago, a member of the North American Numbering Plan (NANP). The telephone numbering plan for the country is known as the National Numbering Plan. It is part of a system used for assigning telephone numbers in Trinidad and Tobago, and functions as a part of the North American Numbering Plan (NANP). It is regulated by the Telecommunications Authority of Trinidad and Tobago, which holds responsibility for telecommunications in the country.
Area codes 202 and 771 are telephone area codes in the North American Numbering Plan (NANP) for Washington, D.C.
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.
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.
A feature group, in North American telephone industry jargon, is most commonly used to designate various standard means of access by callers to competitive long-distance services. They defined switching arrangements from local exchange carriers central offices to interexchange carriers. These arrangements were described in an official tariff of the National Exchange Carrier Association, filed with the Federal Communications Commission (FCC).
020 is the national dialling code for London in the United Kingdom. All subscriber numbers within the area code consist of eight digits and it has capacity for approaching 100 million telephone numbers. The code is used at 170 telephone exchanges in and around Greater London as part of the largest linked numbering scheme in the United Kingdom. In common with all other British area codes the initial '0' is a trunk prefix that is not required when dialling London from abroad.
The New Zealand telephone numbering plan describes the allocation of telephone numbers in New Zealand and the Pitcairn Islands.
Telephone numbers in Oceania use a variety of area codes to denote their location along with their own area code depending on the country's geographic makeup. They also have other prefixes to denote different types of mobile services and international calls. There are exceptions because of regional variations and time zones.
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 landline 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.
In the North American Numbering Plan (NANP), interchangeable NPA and central office codes constituted a change in numbering plan design and policy, to mitigate exhaustion of the numbering resources of the ten-digit telephone numbers used in the closed numbering plan of the NANP.
In the administration of the North American Numbering Plan, central office code protection is a numbering policy for maintaining local seven-digit dialing in communities that extend on both sides of the boundary line between multiple numbering plan areas (NPAs), such as in cross-border towns on state lines. Code protection prevents the use of the same telephone number on both sides by not assigning the same central office code of one NPA in the adjacent NPA.
