Area code 403 is a telephone area code in the North American Numbering Plan (NANP) for the Canadian province of Alberta. The numbering plan area encompasses the southern third of the province, which includes the Calgary area. This numbering plan area is also served by area codes 587, 825, and 368, which form a complex overlay for all of Alberta.
Area code 403 was one of nine Canadian area codes of the original North American area codes assigned by the American Telephone and Telegraph Company (AT&T) in 1947. Its numbering plan area (NPA) originally comprised the entire province of Alberta. During the course of the expansion of telephone service in the Canadian territories, these were serviced primarily with the same area code until the territories received area code 867 on October 21, 1997. [1]
Within only a year, area code 403 was threatened by exhaustion because of the rapid growth of telecommunication services demand for pagers, cellphones, and computer modems, as well as growing competition among providers. On January 25, 1999, the northern two thirds of Alberta, including Edmonton, was split from 403 and assigned the new area code 780. Generally, everything from Red Deer, Lacombe, and Ponoka southward stayed in 403. Permissive dialing of 403 continued across the province until May 18, 1999.
Within a decade, area code 403 was close to exhaustion once again. The projected exhaust date was March 2009. [2] The solution for mitigation was to implement area code 587 as a province-wide overlay for both numbering plan areas of the province. [3] [4] [5] Optional ten-digit dialing began on June 23, 2008 and became mandatory on September 12, 2008. [6] On September 20, 2008, Telus Mobility began to assign 587 telephone numbers to new customers in Calgary and Edmonton.
On April 9, 2016, all three numbering plan areas of the province were overlaid with an additional area code, 825. [7]
On January 21, 2022, the province was once again overlaid with another area code, 368. [8] [9]
The incumbent local exchange carrier (ILEC) in 403 is Telus. Prior to 1997, the larger 403 included EdTel (Edmonton Telephones, now part of Telus) and Northwestel as ILECs. Before 1990, Telus was known as Alberta Government Telephones and was a provincial government department. [10]
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Area code 867 is the area code in the North American Numbering Plan (NANP) for the three Canadian territories, all of which are in Northern Canada. The area code was created on October 21, 1997, by combining regions that were previously served with area code 403 and area code 819 in one numbering plan area (NPA). As the least populated NPA in mainland North America, serving about 130,000 people, it is geographically the largest, at 3,921,739 km2 (1,514,192 sq mi), with Alaska (907) a distant second.
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Area code 780 is a telephone area code in the North American Numbering Plan (NANP) for the Canadian province of Alberta. The numbering plan area comprises the northern two thirds of the province, including the Edmonton area. The area code was established in 1999 in a split of area code 403, which had served the entire province since the establishment of the original North American area codes in 1947. The numbering plan area is also served by area codes 587, 825, and 368, which form a complex overlay for all of Alberta.
Area code 807 is a telephone area code in the North American Numbering Plan (NANP) for the Canadian province of Ontario. The numbering plan area (NPA), comprising only Northwestern Ontario, was created in early 1962 in an area code split of NPA 705. The main reason for the split was not central office prefix exhaustion, but routing efficiency for calls from Western Canada to northwestern Ontario.
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Area codes 587, 825, and 368 are telephone area codes in the North American Numbering Plan (NANP) for the entire Canadian province of Alberta. They form an overlay with area code 403 of southern Alberta, and northern Alberta's 780. The complex overlay involving a total of five area codes in Alberta mandated ten-digit dialing throughout the province.
| North: 780/368/587/825 | ||
| West: 250/778/236/672 | 403 (overlaid with 368, 587, and 825) | East: 306/639 |
| South: 406 | ||
| British Columbia area codes: 236/672/778, 250, 604 | ||
| Saskatchewan area codes: 306, 639 | ||
| Montana area codes: 406 | ||