What is an area code?

An area code is the three-digit prefix at the start of a North American phone number that identifies a specific geographic region — a city, metro area, or part of a state. In the number (212) 555-0100, the 212 is the area code for Manhattan in New York City.

How do I find the area code for a city?

Use the area code directory on this page: type a city, state, or three-digit code and the matching regions appear instantly. You can also browse the popular US area codes and the lookup-by-region sections below.

What is the difference between an area code and a country code?

A country code routes a call to a nation (for example +1 for the United States), while an area code routes it to a region within that nation. You dial the country code first when calling from abroad, then the area code, then the local number.

Can two cities share the same area code?

Yes. A single area code can cover several nearby cities or an entire metro region. As demand for numbers grows, regions are often split or given an additional overlay area code that serves the same geography.

What are toll-free area codes?

Toll-free numbers use special prefixes — 800, 833, 844, 855, 866, 877, and 888 — instead of a geographic area code. The business that owns the number pays for incoming calls, so they are free for the caller. They are popular for customer support and sales lines.

What state is area code 331 in?

Area code 331 is located in Illinois (IL), in the Midwest region of the United States. The capital of Illinois is Springfield.

What time zone is area code 331 in?

Area code 331 operates in the Central Time (CT). If you are calling from a different time zone, make sure to account for the time difference before reaching out during business hours.

How can I get a 331 area code phone number for my business?

You can get a 331 local phone number through letsdial in minutes. Choose the 331 area code, select a local number, and route calls to your team from one cloud dashboard — no hardware required.

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MidwestOverlay code

Area Code 331

Aurora, IL — Illinois

Area code 331 serves Aurora and Illinois. Get a local 331 number to build instant presence in this market.

Introduced in 2007 as an overlay on the 630 code for Chicago's western suburbs. It added capacity to DuPage County.

Get a 331 number ← All area codes

+1 (331) XXX-XXXX

Aurora, IL

LIVE

Connecting…

ONHD Voice

18msLatency

99%Quality

End

State

Illinois (IL)

Capital: Springfield

Time Zone

Central Time (CT)

Region

Midwest

US Census region

Code Type

Overlay

Added for capacity

Cities covered

Where does area code 331 cover?

Area code 331 serves communities across Illinois. Cities below represent the primary coverage area per the NANP.

Aurora
Naperville
Elgin
DuPage County

About Illinois

Illinois phone number landscape

Illinois' 13 area codes reflect Chicago's position as the Midwest's economic powerhouse, from the iconic 312 Loop to tech-heavy North Shore suburbs, with downstate codes covering Springfield and Peoria.

Number format

+1(331)XXX-XXXX

When dialing from outside the US, prefix with +1. Within the US, dial all 10 digits including the area code.

Get a 331 number for your business

History of Area Code 331

Introduced in 2007 as an overlay on the 630 code for Chicago's western suburbs. It added capacity to DuPage County.

For your business

Why get a 331 area code number?

A local 331 number gives your business a genuine connection to the Illinois market — without the overhead of a physical location.

Local Market Access

Reach Aurora customers and businesses with a familiar local number. Naperville hosts a corporate-research and IT-services economy, including a major Bell Labs successor campus. Tech firms increasingly carry 331 numbers as 630 fills up.

Professional Credibility

A 331 number anchors your business in Aurora and Illinois, giving clients and partners a recognizable local point of contact that builds immediate professional trust.

Higher Answer Rates

Local area codes are far less likely to be blocked. A 331 number keeps your outreach out of the spam folder.

Flexible Operations

Start with one 331 number and add more as you grow — all managed from a single letsdial dashboard.

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How to obtain a 331 phone number.

Step 01 · Sign up

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Local advantage

Benefits of a local Illinois number

A 331 area code tells Illinois customers you're local and easy to reach.

Local 331 numbers get answered more often than toll-free or out-of-state calls.
Build local trust and brand recognition without a physical office.
Keep your personal number private with a dedicated 331 business line.

Why local numbers win

+27%Higher answer rate vs. toll-free

+22%More callbacks from local numbers

2.9×Faster trust building with local code

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Area code 331 FAQs

Frequently asked about 331

Area code 331 covers Aurora, Naperville, Elgin, DuPage County in Illinois. It is an overlay code, meaning it serves the same geographic area as an existing area code in the region.

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Get a local 331 number for your business in minutes. No contracts, no hardware — just a trusted local presence in Illinois from day one.

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