Area Code 331: Get an Aurora Phone Number

331 · Aurora

What is the area code for Aurora?

The area code for Aurora, Illinois is 331, with overlay code 630 sharing the same geographic footprint. The 331 area code is a North American Numbering Plan geographic code assigned in 2007, covering the Western Chicago Suburbs region. It serves approximately 1,200,000 residents on the Central Time (CT) (UTC-6 / UTC-5 DST).

The 331 area code has 222 assigned central-office prefixes (NXX codes, the three digits after the area code) across 22 rate centers, with numbers allocated to roughly 35 carriers.

At 222 of the ~792 usable central-office prefixes, the 331 area code has about 28% of its numbering capacity assigned, and that near-exhaustion is part of why overlay code 630 was added to the region. See how 331 compares in our NXX prefix allocation analysis across 338 US area codes. (Prefix data: localcallingguide.com / NANPA, 2026.)

Where is area code 331? Location and map area

Area code 331 is located in Illinois, the United States. Its coverage area centers on Aurora and spans the Western Chicago Suburbs region. If you received a call from a 331 number, the caller's number was assigned in this area — though with number porting and virtual numbers, the person may be calling from anywhere.

The 331 location sits in Central Time (CT), so local business hours run roughly 9 a.m.–5 p.m. CT. Neighboring Illinois area codes include 217, 224, 309.

All Aurora area codes

Aurora is served by 2 area codes across the metro area. 331 is the 2007 addition; the others were added as overlays or for surrounding suburbs.

• 331 (current page) — Overlay on the same metro, assigned 2007
• 630 — Aurora — assigned 1996

Cities served by the 331 area code

The 331 area code covers 5 major cities and towns across the Western Chicago Suburbs region (IL):

Businesses across Aurora and surrounding cities use 331 numbers to project local presence and lift call answer rates. Industry studies of local presence dialing consistently report answer-rate gains of 20–40% over toll-free or out-of-area numbers — a caller ID that matches the recipient's region looks familiar and gets picked up.

331 area code time zone and business hours

The 331 area code is in the Central Time (CT) zone (UTC-6 / UTC-5 DST). Standard business hours in 331 run 9 AM to 5 PM CT.

If you're calling into 331 from a different time zone, factor in the offset. For example, an Eastern Time business calling 331 at 9 AM ET reaches Aurora at 8 AM CT — likely outside standard business hours.

History of the 331 area code

The 331 area code was introduced in 2007 when the North American Numbering Plan was first deployed. As Aurora grew and number demand increased, overlay code 630 was added to serve the same geographic region — a common solution that avoids forcing existing subscribers to change their numbers.

• 1996 630 added to serve the same region
• 2007 331 entered service

Is the 331 area code safe? Spam and scam calls

331 is a legitimate geographic area code for Aurora — it is not a scam code or a premium-rate prefix, and a call from a 331 number is most likely a genuine local caller. The risk is not the area code itself but a tactic called neighbor spoofing: scammers fake their caller ID so an unwanted call appears to come from your own area code, because people answer familiar numbers more readily.

If you get an unexpected 331 call, a few signals point to a likely scam — a pre-recorded message, urgent pressure to act now, a demand for payment by gift card or wire transfer, or anyone asking for passwords, Social Security, or account numbers. Let suspicious calls go to voicemail, never share personal information, and report fraud to the FTC at reportfraud.ftc.gov.

The FCC consumer guide on spoofing explains your rights under the Truth in Caller ID Act. A real Aurora business will leave a clear voicemail and will not pressure you.

US carriers verify caller ID with the STIR/SHAKEN framework, which flags many spoofed numbers as "Spam Likely" before they ring. DialPhone 331 numbers are registered for STIR/SHAKEN attestation, so calls from your business are verified as genuine and reach customers without a false spam label. See the DialPhone guide to VoIP security for more.

Why get a 331 area code number for your business?

Getting a 331 number gives your business three measurable advantages over a toll-free or out-of-area number:

1. Local trust signal. Customers in Aurora recognize 331 as their home area code. Caller ID matching builds immediate credibility for service businesses, sales outreach, and patient communication.
2. Higher answer rate. Calls from a familiar local area code are answered far more often than unknown or toll-free numbers — industry measurements of local presence dialing put the lift at 20–40%, which matters most for outbound sales, appointment confirmations, and time-sensitive service callbacks.
3. Targeted marketing. Businesses serving Aurora and the broader Western Chicago Suburbs can advertise a local number across print, radio, billboards, and digital channels for higher conversion than a national 800 number.

For businesses in Aurora and surrounding cities, top industries that benefit from local 331 presence include Finance, Manufacturing, and Healthcare. DialPhone's AI receptionist is available for every 331 number — never miss a call, even after standard business hours.

How to get a 331 area code number

Setting up a 331 business number with DialPhone takes under 10 minutes:

1. Sign up for a DialPhone plan. Choose any plan starting at $24/user/month. Free 14-day trial, no credit card required.
2. Search available 331 numbers. Filter the DialPhone number inventory by area code, city, or pattern.
3. Choose your number and configure. Assign your new 331 number to a user or team, set up call routing, voicemail, AI receptionist, and business SMS.
4. Port your existing number (optional). Already have a 331 number? Free number porting in 2 to 5 business days with zero service interruption.

New to local numbers? The complete guide to getting a local phone number covers choosing the right area code, porting an existing line, and avoiding spam flags.

331 area code overlay codes

The Western Chicago Suburbs region is served by multiple overlay area codes:

Area Code	Coverage
331	Primary area code for Western Chicago Suburbs, assigned 2007
630	Overlay — same geography (assigned 1996)

All overlay codes serve the same Aurora region. New subscribers may be assigned any available code; existing numbers retain their original prefix.

AI receptionist for 331 area code businesses

Every DialPhone 331 number includes optional AI receptionist coverage, available 24/7. The AI handles calls when your team is unavailable — answering common questions, booking appointments, routing urgent callers to on-call staff, and capturing voicemail with full transcription and intent tagging.

For businesses in Aurora that handle high call volume, run extended hours, or need bilingual support (especially valuable in service areas with diverse customer bases), the AI receptionist reduces voicemail backlog and improves first-call resolution.

All area codes in Illinois

Illinois has 15 active geographic area codes. The 331 area code is part of the same numbering plan as the codes listed below — calls between them are typically local within the state, depending on the carrier.

Nearby area codes

Related area codes in Illinois and the Central Time (CT) region:

• 217 area code — Springfield, Illinois
• 224 area code — Evanston, Illinois
• 309 area code — Peoria, Illinois
• 312 area code — Chicago, Illinois
• 618 area code — East St. Louis, Illinois
• 630 area code — Aurora, Illinois

All Illinois area codes → · Browse all US area codes →

More area codes: ← 330 Akron · 332 New York City →

How this page is verified

DialPhone re-verifies every area code page every 90 days. Area code geography, timezone, and overlay data come from the official North American Numbering Plan Administration (NANPA) database. Pricing reflects the published DialPhone plan tiers — see the pricing page for current details. Number availability varies; check the DialPhone signup flow for live inventory in the 331 region.

What to know before getting a 331 number

• Number availability is finite. Popular Aurora area codes can be inventory-constrained — request specific vanity patterns early.
• Porting timing varies. Most 331 ports complete in 2-5 business days; complex multi-line legacy contracts can take 7-10.
• HIPAA tier required for healthcare. The Core $24 plan doesn't include a BAA — healthcare users need Advanced ($34) or above.