Linked numbering scheme
Encyclopedia
A Linked Numbering Scheme (LNS) is a telephone numbering plan
applied to an area of the country where calling between lines on a number of adjacent exchanges is done without using a dialing code.
The largest LNS in the UK is that for the London telephone area - formerly known as the London Director area
. Here, several million subscribers can call each other by dialing a uniform code. Thus, 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.
area code 202
in 1947 until 1991 when the number of telephone lines exceeded the capacity of one area code, all persons in the City of Washington as well as the adjoining communities in the U.S. States of Maryland
and Virginia
, could call any number in the region by simply dialing the 7 digit local number, even if the number was in a different state. The way this was done was, in the adjoining counties in Maryland and Virginia, in addition to the area code 703 or area code 301 numbers, they would also be assigned the same local number in the 202 area code. This meant a 585-xxxx number in Silver Spring, Maryland would be reachable from outside the area either as a 202-585-xxxx or 301-585-xxxx, but would be called from DC or Virginia as 585-xxxx. It also meant that any prefix
(such as 585 in the above example) in the entire region could not be duplicated.
In some other rural areas in the U.S. where local calling areas cross state lines, numbers in adjoining areas could be called by dialing the 7-digit number without the area code. If the same prefix existed in the caller's area code, they would have to dial it as a long-distance number.
Telephone numbering plan
A telephone numbering plan is a type of numbering scheme used in telecommunications to allocate telephone numbers 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...
applied to an area of the country where calling between lines on a number of adjacent exchanges is done without using a dialing code.
The largest LNS in the UK is that for the London telephone area - formerly known as the London Director area
Director telephone system
The Director System was a system which made it possible to call subscribers at other telephone exchanges without operator intervention in large multi-exchange cities, and to have a mixture of automatic and manual exchanges within these cities...
. Here, several million subscribers can call each other by dialing a uniform code. Thus, for example, anyone calling from an (020) number can reach Transport for London
Transport for London
Transport for London is the local government body responsible for most aspects of the transport system in Greater London in England. Its role is to implement the transport strategy and to manage transport services across London...
travel enquiries by dialing 7222 1234.
Smaller schemes apply outside London. Uxbridge
Uxbridge
Uxbridge is a large town located in north west London, England and is the administrative headquarters of the London Borough of Hillingdon. It forms part of the ceremonial county of Greater London. It is located west-northwest of Charing Cross and is one of the major metropolitan centres...
, for example, has the subscriber trunk dialing (STD) code 01895. Uxbridge exchange is the parent for Denham
Denham
- People :* Carl Denham, fictional character from King Kong* Daryl Denham, British radio DJ* Digby Denham, Australian politician* Dixon Denham, British explorer* Henry Denham, British printer* Henry Mangles Denham, , Royal navy...
, Harefield
Harefield
Harefield is a village in the London Borough of Hillingdon in northwest London, England. It is situated on top of a hill, northwest of Charing Cross, near the Greater London boundary with Buckinghamshire to the west and Hertfordshire to the north...
, Ruislip
Ruislip
Ruislip is a suburban area, centred on an old village in Greater London, and is part of the London Borough of Hillingdon.It was formerly also a parish covering the neighbouring areas of Eastcote, Northwood, Ruislip Manor and South Ruislip in the area. The parish appears in the Domesday Book, and...
and West Drayton
West Drayton
West Drayton is a suburban area in the London Borough of Hillingdon in the far west of London, England. Formerly part of the Yiewsley and West Drayton Urban District of Middlesex, the district became part of Greater London in 1965....
; 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.
United States
In the United States, from the creation of the Washington, D.C.Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
area code 202
Area code 202
Image:Area code 202.svg|right|The area colored red indicates the geographical region of the District of Columbia, served by area code 202poly 0 50 49 54 103 84 111 88 101 107 118 130 143 139 179 140 211 188 238 203 260 240 259 248 248 250 255 262 253 357 1 357 Area codes 571 and 703poly 1 1 0...
in 1947 until 1991 when the number of telephone lines exceeded the capacity of one area code, all persons in the City of Washington as well as the adjoining communities in the U.S. States of Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
and Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
, could call any number in the region by simply dialing the 7 digit local number, even if the number was in a different state. The way this was done was, in the adjoining counties in Maryland and Virginia, in addition to the area code 703 or area code 301 numbers, they would also be assigned the same local number in the 202 area code. This meant a 585-xxxx number in Silver Spring, Maryland would be reachable from outside the area either as a 202-585-xxxx or 301-585-xxxx, but would be called from DC or Virginia as 585-xxxx. It also meant that any prefix
Telephone prefix
A telephone prefix is the first set of digits of a telephone number; in the North American Numbering Plan countries , it is the first three digits out of a seven-digit phone number...
(such as 585 in the above example) in the entire region could not be duplicated.
In some other rural areas in the U.S. where local calling areas cross state lines, numbers in adjoining areas could be called by dialing the 7-digit number without the area code. If the same prefix existed in the caller's area code, they would have to dial it as a long-distance number.