Phone prefixes in St-Constant, QC

In numbers

In-service prefixes

15

Telephone numbers covered

150,000

Carriers

7

Area codes

3

Provinces and territories

1

First assignment

June 13, 2002

Most recent assignment

August 21, 2025

St-Constant’s share of its area codes

Within area code 450, St-Constant accounts for only 10 of 775 prefixes (1.3%): the code is dominated by Granby and spread over 129 rate centres. Within area code 579, St-Constant accounts for only 4 of 644 prefixes (0.6%): the code is dominated by Granby and spread over 126 rate centres. Within area code 354, St-Constant 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 6 prefixes, 40.0% of the total, ahead of 6 other carriers. Code by code: in 450, Videotron Ltd. leads with 4 of 10 prefixes ahead of 3 others; in 579, Videotron Ltd. leads with 2 of 4 prefixes ahead of 2 others; Cogeco Connexion Inc. is the only holder in 354. No carrier holds prefixes in every one of St-Constant’s 3 area codes, while 6 appear in just one.

Wireless and wireline

None of St-Constant’s holders carries a mobility brand in its registered name: all 15 prefixes belong to wireline or wholesale carriers, among them Videotron Ltd, Bell Canada, Cogeco Connexion Inc and Comwave Networks. A call showing a St-Constant number therefore nominally comes from a landline, cable or VoIP platform rather than a locally assigned cellphone.

How the allocation was built up

St-Constant’s dated assignments run from 2002 to 2025. The busiest period was 2005–2009, when 3 prefixes went to 2 carriers. 3 prefixes (20%) carry no date in the register: these are the historic pre-1999 assignments, the wireline bedrock of the rate centre. Since 2020 another 2 prefixes have been added, so the rate centre is still growing.

St-Constant’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 Bell Canada in 2002. The most recent arrivals are Cogeco Connexion Inc. (2025), Fibernetics Corporation (2021) and TELUS Quebec (2019), a sign that new carriers are still asking for numbers in St-Constant.

St-Constant has only 15 prefixes, or 150,000 numbers: a small rate centre, where the arrival of a single new carrier visibly changes the landscape.

Videotron Ltd. leads with 40.0% of the prefixes, but 6 competitors have set up in St-Constant: a market where the incumbent keeps the edge without exclusivity.

Allocation is mature: only 16.7% of the dated prefixes are less than ten years old, most having been handed out in 2005–2009, and 3 prefixes go back to the undated monopoly era. New St-Constant numbers mostly come out of blocks that were assigned long ago.

3 undated in the register.

Dialling a St-Constant number

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

The numbering neighbourhood

St-Constant shares area codes 450, 579 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-Constant number tells you

A number attached to St-Constant 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-Constant: code 450-509 is recorded for Videotron Ltd., so every 450-509-XXXX number (10,000 possible) descends from that assignment. “St-Constant, Quebec” there names a rate centre, not a municipality, and several area codes overlay it.

Every St-Constant prefix

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

Allocated prefixes

All 15 in-service prefixes, grouped by rate centre.

Elsewhere in Quebec