Area Code 343 – Ontario

Geographic Coverage and Administration

Area code 343 is a geographic overlay serving the province of Ontario, Canada, within the North American Numbering Plan (NANP). It covers the same territory as area codes 613 and 683, primarily the eastern portion of Ontario, including the national capital region of Ottawa. The numbering plan area (NPA) 343 was introduced in 2006 to supplement the exhausted 613 code, and in 2021, area code 683 was added as an additional overlay for the same region. This overlay complex ensures a continuous supply of telephone numbers for the growing population and business sectors in cities such as Ottawa, Kingston, Cornwall, Brockville, Pembroke, and Belleville, as well as surrounding rural communities.

Dialing Procedures and Number Format

As part of the NANP, numbers with area code 343 follow the standard 10-digit dialing format: NPA-NXX-XXXX, where NXX is the central office code. For local calls within the overlay region, callers must dial all ten digits, even if the call is to a neighbouring area code. This mandatory 10-digit dialing applies to all local calls, including those between 613, 343, and 683 numbers. For international callers, the country code for Canada is +1, so a typical number would be dialed as +1 343 XXX XXXX. For example, a caller from the United States or any other country would dial +1 343 555 0123 to reach a landline or mobile in Ottawa.

Caller Instructions

• Local callers (within Canada): Dial 343-XXX-XXXX for all calls within the 613/343/683 region. Long-distance calls outside this region require dialing 1-343-XXX-XXXX.
• International callers: Dial your country's exit code (e.g., 011 from the U.S., 00 from most European countries), followed by 1 (Canada's country code), then 343 and the seven-digit local number.

Overlay Considerations and Number Portability

The overlay design means that new telephone numbers in the region may be assigned any of the three area codes (613, 343, or 683), regardless of the subscriber's physical location. This allows customers to keep their existing numbers when changing service providers, thanks to local number portability (LNP). However, it also means that a number with area code 343 does not indicate a specific city or town; it simply identifies the broader eastern Ontario region. For businesses, having a 343 number can be advantageous as it is recognized as a local presence in the Ottawa area, even if the company operates from a different part of the province.

Technical and Regulatory Notes

From a technical standpoint, area code 343 is assigned to both landline and mobile services, and it is not reserved for any specific carrier. The Canadian Radio-television and Telecommunications Commission (CRTC) oversees numbering resources in Canada, ensuring efficient allocation. As with all NANP codes, the prefix is subject to exhaust management, and the introduction of 683 was a proactive measure to avoid future shortages. For VoIP and wireless users, the area code does not affect the quality or routing of calls; it is purely a numbering identifier.