Phone prefixes in Sarnia, ON

In numbers

In-service prefixes

52

Telephone numbers covered

520,000

Carriers

17

Area codes

3

Provinces and territories

1

First assignment

May 12, 2000

Most recent assignment

December 3, 2025

Sarnia’s share of its area codes

Within area code 519, Sarnia accounts for only 24 of 779 prefixes (3.1%): the code is dominated by London and spread over 210 rate centres. Within area code 226, Sarnia accounts for only 17 of 778 prefixes (2.2%): the code is dominated by London and spread over 166 rate centres. Within area code 548, Sarnia accounts for only 11 of 499 prefixes (2.2%): the code is dominated by London and spread over 170 rate centres.

Who holds these numbers

Bell Canada holds the largest share at 14 prefixes, 26.9% of the total, ahead of 16 other carriers. Code by code: in 519, Bell Canada leads with 13 of 24 prefixes ahead of 6 others; in 226, Iristel Inc. leads with 3 of 17 prefixes ahead of 11 others; in 548, Iristel Inc. leads with 3 of 11 prefixes ahead of 6 others. 2 carriers hold prefixes in every one of Sarnia’s 3 area codes, while 10 appear in just one.

Wireless and wireline

15 of Sarnia’s 52 prefixes (28.8%) are held by carriers whose registered name marks a wireless business: TELUS Mobility, Bell Mobility, Rogers Communications Canada Inc. (Wireless) and Fido Solutions Inc. Wireline prefixes still outnumber them, carried by Bell Canada, Iristel Inc, TELUS Integrated Communications and Fibernetics Corporation. 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

Sarnia’s dated assignments run from 2000 to 2025. The busiest period was 2005–2009, when 10 prefixes went to 9 carriers. 14 prefixes (27%) carry no date in the register: these are the historic pre-1999 assignments, the wireline bedrock of the rate centre. Since 2020 another 9 prefixes have been added, so the rate centre is still growing.

Sarnia’s oldest prefixes, the ones the register leaves undated, belong to Bell Canada, Rogers Communications Canada Inc. (Wireless) and Bell Mobility: 4 carriers made up the landscape before competition arrived. The first dated assignment went to Bell Canada in 2000. The most recent arrivals are Cogeco Connexion Inc. (2025), Videotron Ltd. (2023) and InnSysVoice Corp (2018), a sign that new carriers are still asking for numbers in Sarnia.

Sarnia’s 52 prefixes provide 520,000 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 Sarnia: the leader, Bell Canada, holds only 26.9% of the prefixes against 16 competitors, a sign of a highly fragmented market where cable companies, mobility brands and VoIP providers weigh as much as the incumbent.

Demand remains steady: 23.7% of the dated prefixes go back to the last ten years, the most active period being 2005–2009. The rate centre is growing at a regular rather than explosive pace.

14 undated in the register.

Dialling a Sarnia number

Sarnia is served by 3 overlaid area codes (519, 226 and 548). A 548 number is no more “out of town” than a 519 one; from abroad, dial +1 and the full ten digits.

The numbering neighbourhood

Sarnia shares area codes 519, 226 and 548 with at least 20 other rate centres, including London, Kitchener-Waterloo, Windsor, Guelph, Brantford, Chatham, Hespeler and Owen Sound. The largest of them, London, holds 214 prefixes in 226, 519 and 548; the smallest on the list, St. Thomas, has just 15.

What a Sarnia number tells you

A number attached to Sarnia tells you that its prefix was issued to a carrier for this rate centre in Ontario, 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 17 carriers present here or to a VoIP service usable anywhere. Nor does it tell you who is calling: caller ID can be spoofed, and an Ontario area code is easy to borrow to look local.

Reading a register entry for Sarnia: code 519-332 is recorded for Bell Canada, so every 519-332-XXXX number (10,000 possible) descends from that assignment. “Sarnia, Ontario” there names a rate centre, not a municipality, and several area codes overlay it.

Every Sarnia prefix

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

Allocated prefixes

All 52 in-service prefixes, grouped by rate centre.

Elsewhere in Ontario