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US area code · Illinois

815 area code

Where the 815 area code is, its overlay and how to dial a +1 815 number from anywhere.

CoversBelvidere, IllinoisTime zoneCentral (CT)TypeOverlay
Quick answer

The 815 area code is in Belvidere, Illinois, United States (Central (CT)). To call from abroad: +1 815 555-0123. It is an overlay, so all 10 digits are dialled.

StateIllinois
Main areaBelvidere
Time zoneCentral (CT)
TypeOverlay
10-digit dialingRequired
In service since01-Jan-1947

The 815 area code is a geographic North American Numbering Plan (NANP) code covering Belvidere, Illinois. It has been in service since 01-Jan-1947 and sits in the Central (CT) time zone.

Overlay 815 shares its region

Several area codes cover the same geographic area, so two neighbours can have different codes. Because of the overlay, you must dial all 10 digits (area code + number) even for local calls.

815779

How to dial a 815 number

From abroad+1 815 555-0123
Within the US / Canada1 815 555-0123
Locally (same area)815 555-0123

Cities in the 815 area code

A 815 number is usually in one of these places in Illinois — 8 counties.

Belvidere BooneCrystal Lake MchenryDeKalb DekalbFreeport StephensonJoliet WillKankakee KankakeeLoves Park WinnebagoMachesney Park WinnebagoMcHenry ";MchenryRockford WinnebagoRomeoville WillWoodstock Mchenry

Other Illinois area codes

217224309312331447464618630708730773779847861872

Frequently asked questions

Where is the 815 area code?

The 815 area code is in Belvidere, Illinois, United States (Central (CT)).

Is 815 an overlay area code?

Yes. 815 overlays the same region as 779, so callers dial all 10 digits.

Do I have to dial 10 digits for 815?

Yes — dial the area code plus the seven-digit number.

How do I call a 815 number from another country?

Dial your exit code (or +), then 1, then 815, then the number: +1 815 555-0123.

Source: NANPA numbering plan. An area code covers a region, not a precise address — a 815 number does not pinpoint a street or ZIP code.

Number holders in area code 815

Each prefix (the three digits after the area code) is assigned by NANPA to one telephone company. 800 prefixes are in use in 815, shared by 56 companies. The largest holders:

CompanyPrefixesShare
Illinois Bell Tel Co15720%
Frontier North, Inc.13317%
Level 3 Communications, LLC7610%
Cellco Partnership Dba Verizon Wireless506%
Aero North Communications, Inc.435%
New Cingular Wireless PCS, LLC425%

Source: NANPA central office code assignments. A number keeps its original prefix when it is ported to another carrier.

Complaints about 815 numbers

Reports to the FTC, last 30 days
933
Recorded messages or robocalls
61%
Rank among area codes
#52 of 670
Most reported subjects
Other (364)
Reducing your debt (credit cards, mortgage, student loans) (256)
Dropped call or no message (69)

Period Aug 26 – Sep 24, 2026. These are the numbers shown on the caller ID of the reported calls; many are spoofed and do not belong to the real caller.

Source: US Federal Trade Commission, Do Not Call reported calls data (daily files).

All US area codes United States +1 Map of area code 815 — cities & rate centres

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