Area code 343

Area code 613 and overlay area code 343 are area codes for Ottawa and surrounding Eastern Ontario, Canada, in the North American Numbering Plan (NANP). 613 is one of the 86 original area codes in the NANP assigned in October 1947.

The 613 area originally covered all of Ontario with the exception of the Golden Horseshoe, which was in area code 416. The area code has been split twice. In 1953, the Southwestern Ontario portion of 613 was combined with the western portion of 416 to become 519. In 1957 the vast northwestern portion of 613 was combined with the northern portion of 519 to become area code 705. Since 1957, 613 covers only Eastern Ontario, an area extending from Brighton and Deep River eastward to Saint Regis, Quebec.

Ottawa and its twin city in Quebec, Gatineau fall on the boundary between 613 and Quebec's area code 819. However, they share the same local calling area. As a result, local calls could be completed between Ottawa and Hull with only seven digits. A similar situation prevailed in the Washington metropolitan area across three jurisdictions--Washington itself and parts of Maryland and Virginia.

While there are fewer than two million people in the geographic area covered by 613, the bulk of that population lives in the Ottawa area. To preserve seven-digit dialling between Ottawa and Hull, an exchange code protection scheme was implemented so that the same seven-digit local number could not be assigned on both sides of the National Capital Region. Technically, it was only necessary that no two prefixes within the same local calling area be duplicates, but the code protection as implemented reserved the numbers across an entire area code. This meant that if a 1-819 number was being used in Hull, the corresponding 1-613 number could not be used anywhere in eastern Ontario, even in areas a safe distance from the National Capital Region such as Brighton. Similarly, if a 1-613 number was being used in Ottawa-Carleton, the corresponding 1-819 number could not be used anywhere in western Quebec. Federal government offices in Hull duplicated their entire allocation of multiple exchanges worth of numbers available in 613 as part of a "dual dialability" scheme.

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