Phone prefixes in Ste-Therese, QC

In numbers

In-service prefixes

38

Telephone numbers covered

380,000

Carriers

13

Area codes

3

Provinces and territories

1

First assignment

January 24, 2001

Most recent assignment

March 27, 2025

Ste-Therese’s share of its area codes

Within area code 450, Ste-Therese accounts for only 22 of 775 prefixes (2.8%): the code is dominated by Granby and spread over 129 rate centres. Within area code 579, Ste-Therese accounts for only 15 of 644 prefixes (2.3%): the code is dominated by Granby and spread over 126 rate centres. Within area code 354, Ste-Therese 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

Bell Canada holds the largest share at 12 prefixes, 31.6% of the total, ahead of 12 other carriers. Code by code: in 450, Bell Canada leads with 11 of 22 prefixes ahead of 6 others; in 579, Fibernetics Corporation leads with 3 of 15 prefixes ahead of 9 others; Cogeco Connexion Inc. is the only holder in 354. No carrier holds prefixes in every one of Ste-Therese’s 3 area codes, while 8 appear in just one.

Wireless and wireline

6 of Ste-Therese’s 38 prefixes (15.8%) are held by carriers whose registered name marks a wireless business: TELUS Mobility, Fido Solutions Inc and Rogers Communications Canada Inc. (Wireless). Wireline prefixes still outnumber them, carried by Bell Canada, Videotron Ltd, Fibernetics Corporation and Iristel Inc. This is a sort by name, not a licence lookup, and a mobile prefix may have been ported to another network since.

How the allocation was built up

Ste-Therese’s dated assignments run from 2001 to 2025. The busiest period was 2010–2014, when 10 prefixes went to 7 carriers. 12 prefixes (32%) carry no date in the register: these are the historic pre-1999 assignments, the wireline bedrock of the rate centre. Since 2020 another 3 prefixes have been added, so the rate centre is still growing.

Ste-Therese’s oldest prefixes, the ones the register leaves undated, belong to Bell Canada, TELUS Mobility and Videotron Ltd: these carriers made up the landscape before competition arrived. The first dated assignment went to TELUS Mobility in 2001. The most recent arrivals are Cogeco Connexion Inc. (2025), Distributel (2018) and Fibernetics Corporation (2016), a sign that new carriers are still asking for numbers in Ste-Therese.

Ste-Therese’s 38 prefixes provide 380,000 numbers, which corresponds to a mid-sized city or a well-established suburb that every major carrier wants a slice of.

No single carrier dominates Ste-Therese: the leader, Bell Canada, holds only 31.6% of the prefixes against 12 competitors, a sign of a highly fragmented market where cable companies, mobility brands and VoIP providers weigh as much as the incumbent.

Allocation is mature: only 11.5% of the dated prefixes are less than ten years old, most having been handed out in 2010–2014, and 12 prefixes go back to the undated monopoly era. New Ste-Therese numbers mostly come out of blocks that were assigned long ago.

12 undated in the register.

Dialling a Ste-Therese number

Ste-Therese 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

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

What a Ste-Therese number tells you

A number attached to Ste-Therese tells you that its prefix was issued to a carrier for this rate centre in Quebec, most often Bell Canada. It does not tell you where the handset is today: a subscriber may have ported the number to any of the 13 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 Ste-Therese: code 450-419 is recorded for Bell Canada, so every 450-419-XXXX number (10,000 possible) descends from that assignment. “Ste-Therese, Quebec” there names a rate centre, not a municipality, and several area codes overlay it.

Every Ste-Therese prefix

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

Allocated prefixes

All 38 in-service prefixes, grouped by rate centre.

Elsewhere in Quebec