Area code 343 — Ontario
Eastern Ontario (overlay of 613). Overlay assignment, in service since 2010.
At a glance
- Country
- Canada
- Province / territory
- Ontario
- Service area
- Eastern Ontario (overlay of 613)
- Time zone
- Eastern Time (EST/EDT, UTC-5/-4) · current offset -04:00
- Type
- Overlay
- In service since
- 2010
- Country code
- +1 (NANP)
Map
Cities served by 343
Related & overlay area codes
Area code 343 shares geography with 2 other codes serving the same region. A call placed inside this overlay must dial all 10 digits regardless of which code your own line uses.
Carriers operating in 343
The following national and regional telecommunications carriers hold central office (CO) code assignments within numbering plan area 343. Number portability means a phone number originally issued by one carrier may now ride on another carrier's network.
About area code 343
Area code 343 is a Canadian numbering plan area covering Eastern Ontario (overlay of 613). It was placed into service in 2010 as a overlay code, and today operates under the Eastern Time (EST/EDT, UTC-5/-4) time zone.
Numbers in the 343 NPA are issued in central office (CO) blocks of 10,000 to local exchange carriers, who then assign them to subscribers. Because Canada uses a competitive carrier model under CRTC oversight, multiple carriers — both incumbent and competitive — hold blocks within 343. The current carrier of record for any specific number can be looked up via the Canadian Local Number Portability Consortium, but the originally issued carrier is no longer a reliable signal of who actually serves that line.
If you receive a call from a number beginning with 343, the caller is either physically located in or has historically been associated with Eastern Ontario (overlay of 613). The same applies to overlay codes 613, 753: any of these area codes can correspond to a phone in the same geography, and many households carry numbers from two or three different overlays simultaneously across landlines and mobile devices.
To call a number in 343 from outside Canada and the United States, dial your country's international access prefix, then +1 343 followed by the 7-digit local number. Within the NANP, simply dial 1 followed by all 10 digits — or just the 10 digits if you are also located in an overlay region where 7-digit local dialling is no longer permitted.
Frequently asked questions
Where is area code 343?
Area code 343 serves Eastern Ontario (overlay of 613) in Ontario, Canada.
What time zone is 343?
Numbers in 343 are in the Eastern Time (EST/EDT, UTC-5/-4) time zone.
Is 343 a toll-free or mobile-only code?
No. Canadian area codes are geographic — they apply to both landline and mobile numbers in Eastern Ontario (overlay of 613). Toll-free codes in the NANP (800, 833, 844, 855, 866, 877, 888) are a separate category.
Why do I see calls from 343 if I do not know anyone there?
Two reasons. First, mobile portability: someone who moved away from Ontario can keep their 343 number anywhere in the world. Second, scam callers frequently spoof Canadian area codes to appear local. If you do not recognise the number, it is generally safe to let it go to voicemail.