Seven-digit dialing

7-digit dialing7-digit diallingfixed-length seven-digit numberseven digitseven-digitseven-digit diallingseven-digit local callingseven-digit local dialing
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.wikipedia
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North American Numbering Plan

Area codeArea codesArea code(s)
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.
The intent was for subscribers not to have to dial an area code when making a local call or a call within their plan area, resulting in seven-digit dialing.

Central office code protection

exchange code protectioncode protection
Central office code protection made it possible in some low density areas to use seven digits to reach areas in another area code.
Its primary purpose was initially to preserve seven-digit dialing of local calls across a common area code boundary in border communities.

PEnnsylvania 6-5000

212-736-5000telephone number
A few of the largest cities, such as New York, used seven dial pulls ("PENnsylvania 5000" became PEN-5000 and later PEnnsylvania 6-5000, dialled PE6-5000 or 736-5000).
When seven-digit telephone numbers were first assigned in New York in 1920, the three-letter four-number (3L-4N) system had represented the number in the format PENnsylvania 5000.

Area code 202

202Area codes in Washington, D.C.
Washington is thus one of the largest cities where seven-digit dialing is still possible.

Ten-digit dialing

10-digit dialingten-digit diallingten digits
Area code overlay plans introduced a requirement in most areas that calls must include the area code, resulting in a 10-digit dialing requirement.
After the implementation of the North American Numbering Plan, placing a local call within the caller's area code involved only seven-digit dialing.

Area code 506

506
With overlays in several areas (the relief method of choice in Canada since 2000), ten-digit local numbers are now supplanting seven-digit dialing; as of 2019, only four Canadian area codes (506, 709, 807 and 867) are still single-code areas (no overlay) and allow seven-digit local dialing.
Besides 506 & 709, 807 & 867 are the other Canadian area codes to still use 7-digit dialling and have yet to be overlaid.

Area code 709

709
With overlays in several areas (the relief method of choice in Canada since 2000), ten-digit local numbers are now supplanting seven-digit dialing; as of 2019, only four Canadian area codes (506, 709, 807 and 867) are still single-code areas (no overlay) and allow seven-digit local dialing.
For now, this and the three other Canadian area codes, 506, 807 and 867 still use 7-digit dialling and have yet to be overlaid.

Area code 867

867+1-867867 area code
With overlays in several areas (the relief method of choice in Canada since 2000), ten-digit local numbers are now supplanting seven-digit dialing; as of 2019, only four Canadian area codes (506, 709, 807 and 867) are still single-code areas (no overlay) and allow seven-digit local dialing.
It is also one of four Canadian area codes yet to be overlaid, the others being 506, 709 (both of which are currently slated for overlays), and 807 for which seven-digit dialing is still used.

Area code 807

807
With overlays in several areas (the relief method of choice in Canada since 2000), ten-digit local numbers are now supplanting seven-digit dialing; as of 2019, only four Canadian area codes (506, 709, 807 and 867) are still single-code areas (no overlay) and allow seven-digit local dialing.
As a result, 807 is the only area code in Ontario without an overlay, and hence the only one still with 7-digit dialling.

Linked numbering scheme

linked-number area
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.

Telephone number

phone numbertelephone numbersphone numbers
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.

Local call

local phone calls
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.

Telephone exchange

exchangescentral officeexchange
Originally, telephone exchanges consisted of manual boards operated by switchboard operators.

Switchboard operator

telephone operatoroperatortelephonist
Originally, telephone exchanges consisted of manual boards operated by switchboard operators.

Party line (telephony)

party lineparty linestelephone party line
A rural telephone number, often party line, was often up to four digits plus a letter or letter and digits to indicate which of the multiple parties on the line was desired.

New York City

New YorkNew York, New YorkNew York City, New York
A few of the largest cities, such as New York, used seven dial pulls ("PENnsylvania 5000" became PEN-5000 and later PEnnsylvania 6-5000, dialled PE6-5000 or 736-5000).

List of original NANP area codes

original area codesoriginal 86 area codesoriginal area code
The initial 86 area codes were assigned in 1947 as routing codes for operator calls; the first cross-country Bell System direct distance dial call was made in 1951.

Bell System

Bell Operating CompanyBell Operating CompaniesBell Telephone
The initial 86 area codes were assigned in 1947 as routing codes for operator calls; the first cross-country Bell System direct distance dial call was made in 1951.

Direct distance dialing

direct dialdirect distance dialIDDD
The initial 86 area codes were assigned in 1947 as routing codes for operator calls; the first cross-country Bell System direct distance dial call was made in 1951.

Montreal

Montreal, QuebecMontréalMontreal, Canada
Numbers in 2L+4N cities (such as Montréal and Toronto) were systematically lengthened to seven digits in the 1950s, a few exchanges at a time, so that all local numbers were seven digits when direct distance dialling finally came to town.

Toronto

Toronto, OntarioToronto, CanadaToronto, ON
Numbers in 2L+4N cities (such as Montréal and Toronto) were systematically lengthened to seven digits in the 1950s, a few exchanges at a time, so that all local numbers were seven digits when direct distance dialling finally came to town.

Telephone numbering plan

Area codeTelephone codearea codes
Within the multinational calling area administered by the North American Numbering Plan, telephone numbers are composed of three fixed-length fields: a three-digit numbering plan area (NPA) code (area code), a three-digit (NXX) central office code, and a four-digit (XXXX) station number.

Area code 334

334
This dialing plan was incompatible with the introduction of area code 334 and area code 360, and was therefore eliminated by January 1, 1995 in the United States, and by September 1994 in Canada.

Area code 360

360360/564
This dialing plan was incompatible with the introduction of area code 334 and area code 360, and was therefore eliminated by January 1, 1995 in the United States, and by September 1994 in Canada.

Interchangeable NPA code

interchangeable NPA codes
As of 1995, with the introduction of interchangeable NPA codes, nearly all code combinations are useful as NPAs or as NXXes.