The 343 area code is a three-digit code assigned to the North American Numbering Plan (NANP), and it serves Eastern Ontario, Canada, including the nation’s capital, Ottawa. It is not a US area code but is a crucial part of the Canadian telecommunications network, operating as an overlay for the original 613 area code.
If you have a phone number with the 343 area code, or are receiving calls from one, this comprehensive guide will give you all the details on its geographic location, time zone, and how it affects dialing in the region.
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Location and Function of the 343 Area Code
Area code 343 is a regional area code within the Canadian province of Ontario. It covers a broad swathe of the eastern portion of the province.
| Feature | Detail |
| Location | Eastern Ontario, Canada |
| Major City | Ottawa (Canada’s capital) |
| Type | Overlay Code (for 613 and 753) |
| Time Zone | Eastern Time (ET) |
The 343 Overlay Complex
The 343 area code was officially introduced in 2010 as an overlay to the older, original 613 area code.
- What it means: An overlay means that the 343 and 613 area codes cover the exact same geographic territory. New phone numbers assigned in the region may receive either a 613, 343, or the newer 753 area code (added in 2022).
- Mandatory 10-Digit Dialing: Because two or more area codes serve the same region, all local calls within Eastern Ontario require 10-digit dialing (Area Code + 7-digit number), even if the two numbers share the same area code (e.g., calling 343 to 343).
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Key Cities Served by the 343 Area Code
The 343 area code encompasses the entire geographical region historically covered by 613. The area is bordered by Quebec to the east and the U.S. states of New York and Michigan to the south.
Major cities and communities that use the 343 area code include:
- Ottawa (The largest population center)
- Kingston
- Cornwall
- Pembroke
- Brockville
- Belleville
- Hawkesbury
- Carleton Place
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Time Zone Information
The 343 area code lies within the Eastern Time Zone (ET).
- Standard Time: Eastern Standard Time (EST), which is UTC-5:00
- Daylight Saving Time: Eastern Daylight Time (EDT), which is UTC-4:00 hours (observed from early March to early November).
If you are calling the 343 area code from the Western or Central U.S. or Canada, always check the current local time to ensure you are not calling too early or too late.
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How to Dial the 343 Area Code
The full dialing format for the 343 area code follows the NANP standard:
Calling from the U.S. or Another Canadian Area Code
- Dial 1 (The country code for all of NANP).
- Dial the 343 Area Code.
- Dial the 7-digit Local Number.
Local Calls within Eastern Ontario (Mandatory 10-Digit Dialing)
Even if you and the person you are calling are both located in Ottawa and share the 613, 343, or 753 area codes, you must dial all ten digits (Area Code + 7-digit number).
Frequently Asked Questions (FAQ)
Is 343 a U.S. area code?
No. The 343 area code is a Canadian area code that serves the province of Ontario. While it is part of the North American Numbering Plan, it is not assigned to any state in the U.S.
Do I have to pay long-distance charges to call 343 from the U.S.?
Yes, calling the 343 area code from the U.S. is an international long-distance call. While many modern US phone plans (especially unlimited mobile plans) include calling to Canada at no extra charge, you should always verify the terms of your specific phone plan before dialing to avoid unexpected international fees.
What is the difference between 343 and 613?
The 613 area code was the original area code for Eastern Ontario, established in 1947. The 343 area code was introduced in 2010 as an overlay because the supply of 613 numbers was exhausted. They cover the exact same physical region, but numbers with the 343 code were issued more recently.
