Phone prefixes in St-Denis, QC

In numbers

In-service prefixes

8

Telephone numbers covered

80,000

Carriers

7

Area codes

3

Provinces and territories

1

First assignment

February 3, 2005

Most recent assignment

August 21, 2025

St-Denis’s share of its area codes

Within area code 579, St-Denis accounts for only 4 of 644 prefixes (0.6%): the code is dominated by Granby and spread over 126 rate centres. Within area code 450, St-Denis accounts for only 3 of 775 prefixes (0.4%): the code is dominated by Granby and spread over 129 rate centres. Within area code 354, St-Denis accounts for only 1 of 56 prefixes (1.8%): the code is dominated by Valleyfield and spread over 49 rate centres.

Who holds these numbers

Videotron Ltd. holds the largest share at 2 prefixes, 25.0% of the total, ahead of 6 other carriers. Code by code: in 579, Cooptel leads with 1 of 4 prefixes ahead of 3 others; in 450, Videotron Ltd. leads with 2 of 3 prefixes ahead of 1 others; Cogeco Connexion Inc. is the only holder in 354. No carrier holds prefixes in every one of St-Denis’s 3 area codes, while 7 appear in just one.

Wireless and wireline

None of St-Denis’s holders carries a mobility brand in its registered name: all 8 prefixes belong to wireline or wholesale carriers, among them Videotron Ltd, Bell Canada, Cogeco Connexion Inc and Cooptel. A call showing a St-Denis number therefore nominally comes from a landline, cable or VoIP platform rather than a locally assigned cellphone.

How the allocation was built up

St-Denis’s dated assignments run from 2005 to 2025. The busiest period was 2020–2024, when 3 prefixes went to 3 carriers. 1 prefixes (13%) carry no date in the register: these are the historic pre-1999 assignments, the wireline bedrock of the rate centre. Since 2020 another 4 prefixes have been added, so the rate centre is still growing.

St-Denis’s oldest prefixes, the ones the register leaves undated, belong to Bell Canada: this carrier made up the landscape before competition arrived. The first dated assignment went to Videotron Ltd. in 2005. The most recent arrivals are Cogeco Connexion Inc. (2025), ISP Telecom Inc. (2022) and Fibernetics Corporation (2021), a sign that new carriers are still asking for numbers in St-Denis.

St-Denis has just 8 prefixes (80,000 numbers): a very small rate centre, typical of a village or rural area served by a single switching office.

No single carrier dominates St-Denis: the leader, Videotron Ltd., holds only 25.0% of the prefixes against 6 competitors, a sign of a highly fragmented market where cable companies, mobility brands and VoIP providers weigh as much as the incumbent.

Growth is recent: 57.1% of the dated prefixes were assigned in the last ten years, peaking in 2020–2024. St-Denis is among the rate centres where demand for numbers is still rising quickly.

1 undated in the register.

Dialling a St-Denis number

St-Denis is served by 3 overlaid area codes (579, 450 and 354). A 354 number is no more “out of town” than a 579 one; from abroad, dial +1 and the full ten digits.

The numbering neighbourhood

St-Denis shares area codes 579, 450 and 354 with at least 20 other rate centres, including Granby, Joliette, St-Jerome, St-Hyacinthe, Longueuil, Ste-Therese, St-Lambert and Sorel. The largest of them, Granby, holds 52 prefixes in 354, 450 and 579; the smallest on the list, Beloeil, has just 17.

What a St-Denis number tells you

A number attached to St-Denis tells you that its prefix was issued to a carrier for this rate centre in Quebec, most often Videotron Ltd.. It does not tell you where the handset is today: a subscriber may have ported the number to any of the 7 carriers present here or to a VoIP service usable anywhere. Nor does it tell you who is calling: caller ID can be spoofed, and a Quebec area code is easy to borrow to look local.

Reading a register entry for St-Denis: code 450-213 is recorded for Videotron Ltd., so every 450-213-XXXX number (10,000 possible) descends from that assignment. “St-Denis, Quebec” there names a rate centre, not a municipality, and several area codes overlay it.

Every St-Denis prefix

Each row is an in-service central-office code recorded for St-Denis, with its original holder and year of assignment.

Had a call from a St-Denis number?

No clear pattern in reports on these numbers yet. If a call worried you:

1. Call back on a number you trust

   If a caller says they are your bank, the Canada Revenue Agency, a courier or your phone company, hang up and call the organization on the number from its website or your statement, never the number that called you. Caller ID can be faked.

2. Report the fraud

   Report the call or text to the Canadian Anti-Fraud Centre online or at 1-888-495-8501. If you lost money or gave out personal details, tell your bank first, then your local police.

   Report to the Canadian Anti-Fraud Centre ↗

3. Register on the National Do Not Call List

   Registering a landline or mobile on the National DNCL is free. Registered charities, political parties, newspapers and companies you already do business with may still call.

   National Do Not Call List ↗Who can still call you ↗

4. Forward suspicious texts to 7726

   Forward a scam or spam text to 7726 (SPAM on the keypad). It's free, and your carrier uses it to block the sender. Don't tap links or reply.

   Get Cyber Safe: forwarding to 7726 ↗

Allocated prefixes

All 8 in-service prefixes, grouped by rate centre.

Elsewhere in Quebec