343 Area Code: Ottawa, ON | Location & Time Zone

The 343 area code serves Ottawa, Ontario, and surrounding regions in Eastern Ontario, Canada. Introduced in 2010 as an overlay to the existing 613 area code, the 343 area code ensures continued availability of phone numbers in one of Canada’s fastest-growing metropolitan areas. Whether you’re calling Ottawa for business, planning to relocate, or simply need to understand local telecommunications, this comprehensive guide covers everything you need to know about the 343 area code.

What is the 343 Area Code?

The 343 area code is a telephone area code serving Ottawa, Ontario, and the surrounding Eastern Ontario region. It was established on May 17, 2010, as an overlay area code to supplement the original 613 area code. An overlay means that both 613 and 343 serve the same geographic region, with new phone numbers being assigned either code depending on availability. This approach was implemented to address the growing demand for telephone numbers in the Ottawa-Gatineau metropolitan area without requiring existing customers to change their phone numbers.

The 343 area code covers Canada’s capital city along with numerous municipalities, townships, and rural communities throughout Eastern Ontario. It serves a diverse population that includes government workers, technology professionals, students, and residents across urban and rural settings.

343 Area Code Location & Coverage

Cities and Regions Covered

The 343 area code covers an extensive region of Eastern Ontario. Major cities and communities within this area code include Ottawa (the nation’s capital), Cornwall, Brockville, Pembroke, Smiths Falls, Hawkesbury, Petawawa, Arnprior, Carleton Place, Rockland, Kemptville, Winchester, Alexandria, and Casselman. The coverage area extends from the Quebec border in the east to areas west of Ottawa, and from the St. Lawrence River in the south to the Ottawa Valley in the north.

Ottawa itself is the primary city served by the 343 area code, home to Parliament Hill, numerous national museums, and a thriving technology sector often referred to as “Silicon Valley North.” Beyond Ottawa, the area code serves both suburban communities and rural regions, including agricultural areas, cottage country, and historic towns along the Rideau Canal and St. Lawrence River.

Geographic Coverage Map

The 343 area code spans approximately 19,000 square kilometers of Eastern Ontario. The region is bordered by Quebec to the east and north, with the Ottawa River forming a natural boundary. To the south, the coverage area extends to the St. Lawrence River and the international border with New York State. The western boundary encompasses communities in Lanark County and parts of Renfrew County. This diverse geographic area includes urban centers, suburban developments, agricultural land, forests, and numerous lakes and waterways.

Time Zone Information

The 343 area code region observes Eastern Time, switching between Eastern Standard Time (EST) during winter months and Eastern Daylight Time (EDT) from the second Sunday in March to the first Sunday in November. This time zone is shared with major cities including Toronto, Montreal, and New York City, making coordination with these business centers straightforward.

343 Area Code Details

History of 343 Area Code

When Was 343 Created?

The 343 area code was officially introduced on May 17, 2010, by the Canadian Numbering Administrator. It was created in response to the depletion of available phone numbers in the 613 area code, which had served Eastern Ontario since 1947. The rapid population growth in Ottawa and surrounding communities, combined with increased demand for phone numbers due to mobile phones, fax lines, and internet services, necessitated the addition of a new area code to ensure adequate numbering resources.

Rather than splitting the 613 area code geographically, which would have required many customers to change their phone numbers, telecommunications regulators chose to implement an overlay. This decision meant that both 613 and 343 would serve the identical geographic area, with new numbers being assigned from either code pool as needed.

Area Code Changes and Overlays

The introduction of 343 as an overlay to 613 marked a significant change in dialing procedures for Eastern Ontario residents. Prior to May 2010, local calls within the 613 area could be completed by dialing just seven digits. With the overlay implementation, ten-digit dialing became mandatory for all local calls, meaning callers must dial the area code plus the seven-digit phone number even when calling within the same area code region.

The 613 area code itself has historical significance as one of the original 86 area codes created in 1947 under the North American Numbering Plan. It originally covered all of Eastern Ontario but was reduced in size in 1953 when the 705 area code was created for Northern Ontario. The 343 overlay represents the most recent change to numbering resources in this region, ensuring telephone number availability for future growth.

How to Call 343 Area Code

Dialing Within the Area Code

When making local calls within the 343 or 613 area code region, you must use ten-digit dialing. This means dialing the full area code followed by the seven-digit phone number, even if you are calling someone in the same area code. The format is: 343-XXX-XXXX or 613-XXX-XXXX. You do not need to dial “1” before the area code for local calls within Eastern Ontario, though some phone systems may accept this format as well.

Dialing From Other Area Codes

When calling a 343 number from elsewhere in Canada or the United States, dial 1 followed by the area code and seven-digit number. The format is: 1-343-XXX-XXXX. This is the standard long-distance dialing format within the North American Numbering Plan, which encompasses Canada, the United States, and several Caribbean nations. Long-distance charges may apply depending on your phone plan, though many modern plans include unlimited calling within Canada and the US.

International Dialing

To call a 343 area code number from outside North America, dial your country’s international access code (often 00 or 011), followed by Canada’s country code (1), then the area code and phone number. The complete format is: +1-343-XXX-XXXX. For example, from the United Kingdom, you would dial 00-1-343-XXX-XXXX. From Australia, you would dial 0011-1-343-XXX-XXXX. International calling rates apply and vary by carrier and destination country.

Nearby Area Codes

The 343 area code is geographically close to several Quebec area codes, particularly 819 and 873, which serve Gatineau and Western Quebec just across the Ottawa River. Many Ottawa residents work in Gatineau and vice versa, making these cross-provincial calls common. The region also borders area codes serving Montreal (514, 438, 450) to the east and Toronto area codes (416, 647, 437, 905, 289, 365) to the southwest. For practical information about coordinating calls across time zones, visit Current Local Times Around the World.

Population & Demographics

The 343 area code region serves a population of approximately 1.4 million people, with the Ottawa-Gatineau metropolitan area accounting for roughly 1.1 million residents on the Ontario side. Ottawa itself has a population of over 1 million within city limits, making it Canada’s fourth-largest city. The population is diverse and multilingual, with significant English-speaking and French-speaking communities, as well as immigrants from around the world.

The region’s economy is anchored by the federal government, which employs tens of thousands of workers in Ottawa. The technology sector is also substantial, with major employers including Shopify, numerous telecommunications companies, and defense contractors. Education and healthcare are significant economic drivers, with institutions like the University of Ottawa, Carleton University, and The Ottawa Hospital providing employment and services. Tourism plays an important role, with millions visiting Parliament Hill, national museums, and seasonal attractions like the Rideau Canal Skateway and Canadian Tulip Festival annually.

Beyond Ottawa, the 343 area code region includes smaller cities with distinct economic profiles. Cornwall has manufacturing and distribution sectors, Pembroke serves as a regional center for the Ottawa Valley, and communities along the St. Lawrence River benefit from tourism and cross-border commerce with New York State. Rural areas maintain agricultural traditions while also supporting recreational and seasonal residents attracted to the region’s natural beauty.

Frequently Asked Questions

Do I need to dial the area code for local calls in Ottawa?

Yes, ten-digit dialing is mandatory for all calls within the 343 and 613 area code region, even for local calls. You must dial the area code (343 or 613) followed by the seven-digit phone number. This requirement was implemented when the 343 overlay was introduced in 2010.

Is 343 only for mobile phones or also landlines?

The 343 area code is used for both mobile phones and landlines. When the overlay was implemented, new phone numbers of all types—residential landlines, business lines, mobile phones, and fax numbers—could be assigned either a 613 or 343 area code depending on availability.

Can I request a 613 number instead of 343?

Number assignment depends on availability within your service provider’s inventory. While you can request a specific area code, there is no guarantee that 613 numbers will be available, as many have already been assigned. Some providers may charge fees for specific number requests or searches.

Will there be another area code added to Ottawa?

As of 2025, the 343 and 613 area codes continue to serve the region adequately. Telecommunications regulators monitor numbering resources and would introduce another overlay or implement other solutions if number exhaustion becomes a concern in the future. Any such changes would be announced well in advance to allow businesses and residents to prepare.

What time zone is the 343 area code in?

The 343 area code observes Eastern Time, which is UTC-5 during Eastern Standard Time (winter) and UTC-4 during Eastern Daylight Time (summer). Daylight saving time is observed from the second Sunday in March through the first Sunday in November. If you need to schedule calls or meetings across different zones, check out our Timer Tools for accurate scheduling assistance.

Is 343 the same as 613?

Yes, the 343 and 613 area codes cover exactly the same geographic region in Eastern Ontario. They are overlay area codes, meaning both serve the identical territory. The only difference is when the phone number was assigned—newer numbers are more likely to have the 343 area code, while older numbers typically have 613.

Are calls between 343 and 613 numbers considered long distance?

No, calls between 343 and 613 numbers within the same local calling area are treated as local calls, not long distance. Since both area codes cover the same region, a call from a 343 number in Ottawa to a 613 number in Ottawa is a local call. However, calling from Ottawa to distant communities within the area code region may incur long-distance charges depending on your phone plan and the specific calling area boundaries.

Conclusion

The 343 area code is an essential part of telecommunications infrastructure serving Ottawa and Eastern Ontario. Introduced in 2010 as an overlay to the historic 613 area code, it ensures continued availability of phone numbers in this growing region while preserving existing numbers. Whether you’re a resident, business owner, or visitor, understanding the 343 area code helps you navigate local calling procedures and connect with Canada’s vibrant capital city. The region’s combination of government, technology, education, and cultural institutions makes it a dynamic area with continuing demand for telecommunications services. For more helpful guides on time zones and telecommunications topics, explore our Blog Guides Section for additional resources.