343 Area Code: Ottawa and Eastern Ontario, Canada Guide

Introduction

The 343 area code is not in the United States. It covers Eastern Ontario, Canada, centered on the national capital, Ottawa. From there it stretches out through Kingston, Belleville, Brockville, and Pembroke.

This guide answers where 343 is located and why it isn't a US area code. It covers the federal-government and tech economy behind the region, plus its Eastern Time calling window. It explains the code's 2010 origin as an overlay to the 613 area code. And it shows how to put an Eastern Ontario number in front of customers in minutes.

Where the 343 Area Code Reaches

343 covers Eastern Ontario. It shares its entire territory with the older 613 area code and the newer 753 overlay rather than covering separate ground. All three prefixes ring inside the same Canadian counties, never inside the US.

• Ottawa — Canada's national capital and the region's largest city, home to Parliament Hill and the federal public service
• Kingston — the historic city on Lake Ontario, home to Queen's University and the Royal Military College
• Belleville — the Bay of Quinte region's largest city, midway between Ottawa and Toronto
• Brockville — the St. Lawrence River city known as the Canadian gateway to the Thousand Islands
• Pembroke — the Ottawa Valley city anchoring the region's northwestern edge

The footprint pairs federal-government administration with a growing tech sector and historic university towns. So a 343 area code line can signal a federal-department contractor in Ottawa, a Kingston university vendor, or a Pembroke local business. One prefix carries several distinct Eastern Ontario identities.

Ottawa: Federal Government and Parliament Hill

Ottawa dominates the 343 footprint as Canada's seat of government, and few cities anywhere have an economy this concentrated around a single employer type.

Parliament Hill and the Federal Public Service

Parliament Hill has housed Canada's federal government since 1866. The federal public service remains Ottawa's largest employer by a wide margin. It supports a dense network of government contractors, consultants, and lobbying firms across the city.

National Museums and Tourism

Ottawa's status as National Capital brings the Canadian Museum of History, the National Gallery of Canada, and the Canadian War Museum together in one city. That draws steady tourism and event traffic, layering a hospitality economy on top of the government sector.

The Rideau Canal is a UNESCO World Heritage Site running through the heart of downtown Ottawa. Every winter it freezes into the world's largest naturally maintained skating rink. That turns the federal capital into one of the country's most recognizable seasonal tourist draws.

Ottawa's Tech Sector and Kingston's Universities

Beyond government, the 343 footprint carries a genuine technology sector in Ottawa and a university-driven economy in Kingston.

Shopify and Ottawa's "Silicon Valley North" Legacy

Ottawa earned the nickname "Silicon Valley North" during the 1990s and 2000s, anchored by Nortel Networks, once one of the world's largest telecommunications equipment makers, before its collapse in 2009. Shopify, the e-commerce platform now used by more than a million businesses worldwide, has since become Ottawa's flagship tech employer, keeping its headquarters in the city.

Kinaxis, a supply-chain management software company, also keeps its headquarters in Ottawa. It adds a second major homegrown tech employer alongside Shopify, giving the region a genuine software-industry base beyond its government contracts.

Queen's University and the Royal Military College in Kingston

Kingston anchors the western edge of the 343 footprint around two major institutions. The first is Queen's University, one of Canada's oldest and most respected research universities. The second is the Royal Military College of Canada, the country's federal military academy. Together they give Kingston an academic and defense-adjacent economy distinct from Ottawa's government-and-tech base.

Fort Henry, a 19th-century fortification overlooking the city, still stands as a National Historic Site and living-history museum. It gives Kingston a heritage-tourism draw alongside its university and military-academy economy.

Brockville and the Thousand Islands

Brockville sits on the Canadian shore of the St. Lawrence River, directly across from New York's Thousand Islands region. That gives the smaller city a cross-border tourism economy built on boating, fishing, and the same island-studded river that draws visitors to the American side.

For a business working the wider Ontario market, the 343 area code shares its overlay approach with London's 226 area code further west.

letsdial's virtual number platform covers both regions from the same dashboard.

The full history of how regulators handle splits and overlays across North America is documented in the FCC's overview of area code overlays.

Time Zone and Calling Hours for the 343 Area Code

The entire 343 area code observes Eastern Time — UTC-5 (EST) in winter and UTC-4 (EDT) during Daylight Saving. Eastern Ontario shares the clock with Toronto, Montreal, and New York.

West Coast teams calling area code 343 are three hours behind. Late-morning Pacific outreach lands mid-afternoon in Eastern Ontario, so plan around the gap to catch the full business day.

343 History

Eastern Ontario's original area code, 613, was assigned in 1947. It once covered most of Ontario outside Toronto, before decades of splits narrowed it down to the Ottawa region and the surrounding counties.

Ottawa's population and phone demand grew through the 2000s. The 343 area code was added as an overlay on May 17, 2010. It covers the exact same territory as 613 rather than dividing the region into new ground.

That decision mirrored the approach regulators were taking across dense North American markets at the time. Rather than force businesses and residents to change long-established 613 numbers, an overlay let the region carry two prefixes at once.

Continued growth pushed the region toward exhaustion again, and a third overlay, 753, joined the same complex on March 26, 2022. All three codes — 613, 343, and 753 — now share identical Eastern Ontario territory, with 10-digit dialing required for every local call.

How to Get a 343 Area Code Number

1. 1Cloud phone platform — search available 343 numbers in real time and activate a line the same day, with no hardware and no technician visit.
2. 2Port your existing number — already run a 343 or 613 line on another carrier? Move it over without downtime and keep the number active through the transition.
3. 3Wireless SIM or landline carrier — valid for a single physical handset, but slower to provision and harder to scale seat by seat.

With letsdial, a UCaaS (Unified Communications as a Service) platform built for exactly this, a 343 number provisions in under three minutes on a free trial, no credit card required, so an Eastern Ontario presence can be answering calls the same afternoon, whether that's a government-adjacent office or a remote team representing the region from anywhere in North America.

Call Trust in Eastern Ontario

The 343 area code market runs on federal-government procurement relationships, tech-sector referrals, and university vendor channels — settings where an unknown out-of-region number gets screened before it's answered. A recognizable local prefix earns the first hearing, and in a market built on government and institutional relationships, that first impression often decides whether the conversation happens.

STIR/SHAKEN for Government, Tech, and University Contacts

Apply STIR/SHAKEN attestation so every outbound 343 call arrives verified with your registered business name on screen — Canada's CRTC mandated STIR/SHAKEN across Canadian carriers starting in 2021, the same authentication framework used in the US. As a UCaaS provider, letsdial registers your text campaigns for compliance from day one and warms new numbers before scaling volume, so a verified line reads as Eastern Ontario-local rather than out-of-area.

A trusted 343 line is the difference between a federal-department contact or a Kingston university vendor picking up the call and routing it straight to voicemail.

Conclusion

The 343 area code covers Eastern Ontario, Canada — not the United States — centered on Ottawa's federal government and tech sector, with Kingston's universities and the smaller cities of Belleville, Brockville, and Pembroke rounding out the region. From Parliament Hill to Shopify's headquarters, it identifies a business as genuinely Eastern Ontario.

Standing up a line takes minutes on a cloud UCaaS platform, with STIR/SHAKEN attestation so calls arrive verified rather than flagged. Put a 343 number in front of government contacts, tech partners, and university vendors, and let a familiar prefix open the door first, with letsdial handling the setup end to end.

Frequently Asked Questions