Phone prefixes in St. Isidore, ON

In numbers

In-service prefixes

6

Telephone numbers covered

60,000

Carriers

6

Area codes

3

Provinces and territories

1

First assignment

August 6, 2015

Most recent assignment

January 5, 2026

St. Isidore’s share of its area codes

Within area code 343, St. Isidore accounts for only 3 of 641 prefixes (0.5%): the code is dominated by Ottawa-Hull and spread over 116 rate centres. Within area code 753, St. Isidore accounts for only 2 of 103 prefixes (1.9%): the code is dominated by Ottawa-Hull and spread over 62 rate centres. Within area code 613, St. Isidore accounts for only 1 of 772 prefixes (0.1%): the code is dominated by Ottawa-Hull and spread over 132 rate centres.

Who holds these numbers

Bell Canada holds the largest share at 1 prefixes, 16.7% of the total, ahead of 5 other carriers. Code by code: in 343, Fibernetics Corporation leads with 1 of 3 prefixes ahead of 2 others; in 753, ISP Telecom Inc. leads with 1 of 2 prefixes ahead of 1 others; Bell Canada is the only holder in 613. No carrier holds prefixes in every one of St. Isidore’s 3 area codes, while 6 appear in just one.

Wireless and wireline

None of St. Isidore’s holders carries a mobility brand in its registered name: all 6 prefixes belong to wireline or wholesale carriers, among them Bell Canada, Fibernetics Corporation, ISP Telecom Inc and InnSysVoice Corp. A call showing a St. Isidore number therefore nominally comes from a landline, cable or VoIP platform rather than a locally assigned cellphone.

How the allocation was built up

St. Isidore’s dated assignments run from 2015 to 2026. The busiest period was 2015–2019, when 2 prefixes went to 2 carriers. 1 prefixes (17%) 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.

St. Isidore’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 InnSysVoice Corp in 2015. The most recent arrivals are Rogers Communications Canada Inc. (Cable) (2026), ISP Telecom Inc. (2023) and Fibernetics Corporation (2022), a sign that new carriers are still asking for numbers in St. Isidore.

St. Isidore has just 6 prefixes (60,000 numbers): a very small rate centre, typical of a village or rural area served by a single switching office.

No single carrier dominates St. Isidore: the leader, Bell Canada, holds only 16.7% of the prefixes against 5 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: 60.0% of the dated prefixes were assigned in the last ten years, peaking in 2015–2019. St. Isidore is among the rate centres where demand for numbers is still rising quickly.

1 undated in the register.

Dialling a St. Isidore number

St. Isidore is served by 3 overlaid area codes (343, 753 and 613). A 613 number is no more “out of town” than a 343 one; from abroad, dial +1 and the full ten digits.

The numbering neighbourhood

St. Isidore shares area codes 343, 753 and 613 with at least 20 other rate centres, including Ottawa-Hull, Kingston, Belleville, Cornwall, Kanata-Stittsville, Brockville, Smiths Falls and Bancroft. The largest of them, Ottawa-Hull, holds 441 prefixes in 343, 613 and 753; the smallest on the list, Cumberland, has just 11.

What a St. Isidore number tells you

A number attached to St. Isidore 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 6 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 St. Isidore: code 613-524 is recorded for Bell Canada, so every 613-524-XXXX number (10,000 possible) descends from that assignment. “St. Isidore, Ontario” there names a rate centre, not a municipality, and several area codes overlay it.

Every St. Isidore prefix

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

Allocated prefixes

All 6 in-service prefixes, grouped by rate centre.

Elsewhere in Ontario