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Sent TeamMay 3, 2025 / area code / Article

Area Code 331: Cities, Coverage, and Telecom Insights

Area code 331 is an overlay for 630, serving Chicago's western suburbs since 2007. Covers DuPage, Cook, Kane, & Will counties. Includes cities like Naperville (41.78N), Bolingbrook (41.69N). Ten-digit dialing is mandatory. Explore telecom insights and regulatory details from the ICC.

Area Code 331: Cities, Coverage, and Telecom Insights

Area Code 331 is an essential part of the telecommunications infrastructure in Chicago's western suburbs. Serving parts of DuPage, Cook, Kane, and Will counties in Illinois, this area code supports a growing population and is vital for both residential and business communications.

What Is Area Code 331?

Area Code 331 is an overlay for the existing 630 area code, introduced to meet the increasing demand for phone numbers in the region. Implemented on October 7, 2007, it ensures that residents and businesses in Chicago's western suburbs continue to have access to necessary telecommunications services.

Geographic Coverage of Area Code 331

Area Code 331 covers a wide range of cities in Chicago's western suburbs. Here are some of the major cities included in this area code:

CityLatitudeLongitude
Addison, IL41.9317-87.98896
North Aurora, IL41.80614-88.3273
Bartlett, IL41.99503-88.18563
Batavia, IL41.85003-88.31257
Bensenville, IL41.95503-87.94007
Bloomingdale, IL41.95753-88.0809
Bolingbrook, IL41.69864-88.0684
Carol Stream, IL41.91253-88.13479
Darien, IL41.75198-87.97395
Downers Grove, IL41.80892-88.01117
Elmhurst, IL41.89947-87.94034
Glen Ellyn, IL41.87753-88.06701
Glendale Heights, IL41.91031-88.07174
Hanover Park, IL41.99947-88.14507
Lisle, IL41.80114-88.07479
Lombard, IL41.88003-88.00784
Naperville, IL41.78586-88.14729
Roselle, IL41.98475-88.07979
Saint Charles, IL41.91419-88.30869
Streamwood, IL42.02558-88.17841
Villa Park, IL41.88975-87.98895
West Chicago, IL41.88475-88.20396
Westmont, IL41.79586-87.97562
Wheaton, IL41.86614-88.10701
Woodridge, IL41.74697-88.05034

Telecom Services and Carriers

Area Code 331 is supported by major telecommunications carriers, offering a variety of services:

  • AT&T
  • Verizon
  • T-Mobile
  • Sprint

These carriers provide both landline and wireless services, including Voice over Internet Protocol (VoIP) options, to ensure comprehensive coverage and connectivity.

Regulatory Information

Area Code 331 is regulated by the Illinois Commerce Commission (ICC), which oversees telecommunications services within the state. The North American Numbering Plan Administration (NANPA) also plays a critical role in managing numbering resources, ensuring compliance with national guidelines.

  • Dialing Requirements: Ten-digit dialing is mandatory.
  • Regulatory Body: Illinois Commerce Commission (ICC)

Historical Context

  • August 3, 1996: Area code 630 was created from a split of area code 708.
  • October 7, 2007: 331 was introduced as an overlay to accommodate the growing need for additional phone numbers.

Conclusion

Area Code 331 is a vital component of the telecommunications framework in Chicago's western suburbs. It supports a diverse range of services and meets the region's growing demand for phone numbers. For more information on area codes and telecommunications regulations, visit the North American Numbering Plan Administration (NANPA).


Explore more about area codes in Illinois by checking out related articles on our site. For specific queries or assistance, contact your local telecom provider.

Frequently Asked Questions

What area code is used in Naperville, Illinois, and when was it implemented?

Naperville, Illinois is covered by area code 331, which was implemented as an overlay for area code 630 on October 7, 2007.

Which area code is an overlay for 630 in Illinois, and what does it mean?

Area code 331 is an overlay for 630, meaning they both serve the same geographic area. It was introduced due to increased demand for phone numbers and requires ten-digit dialing.

Which cities in DuPage County use area code 331 in Illinois?

Several cities in DuPage County, including Addison, Bartlett, Bloomingdale, Carol Stream, Darien, Downers Grove, Elmhurst, Glen Ellyn, Glendale Heights, Lisle, Lombard, Naperville, Roselle, Villa Park, West Chicago, Westmont, Wheaton, and Woodridge, use area code 331.

What area code covers Bartlett, Illinois, and what counties are included in its coverage?

Bartlett, Illinois, is covered by area code 331, which spans portions of DuPage, Cook, Kane, and Will counties.

What is the area code for West Chicago, and when did it go into effect?

The area code for West Chicago is 331, and it was activated on October 7, 2007, overlaying the existing 630 area code.

What area code should I use to call Bolingbrook, Illinois, and which regulatory agency oversees it?

You should use area code 331 to call Bolingbrook, Illinois. The Illinois Commerce Commission (ICC) oversees telecommunications services in this area.

Which telecommunications carriers support area code 331 in the Chicago western suburbs?

Major carriers like AT&T, Verizon, T-Mobile, and Sprint provide service in the 331 area code, offering landline, wireless, and VoIP options.

What led to the creation of area code 331 in Chicago's western suburbs?

Area code 331 was created to address the increasing demand for phone numbers in Chicago's western suburbs, ensuring residents and businesses have sufficient access to telecommunications services.

What is the area code of Saint Charles, Illinois, and what is its relation to area code 630?

Saint Charles, Illinois, uses area code 331, which is an overlay of area code 630, serving the same geographic region and requiring 10-digit dialing.

When was area code 630 created, and what led to its overlay by 331 later on?

Area code 630 was created on August 3, 1996. The overlay area code 331 was introduced on October 7, 2007, to handle the rising demand for phone numbers.

Where can I find more information about the regulations for area code 331?

You can find more information on the regulations for area code 331 on the Illinois Commerce Commission (ICC) and the North American Numbering Plan Administration (NANPA) websites.

What area code is Chicago western suburbs?

Chicago's western suburbs primarily use area code 331. This area code is an overlay to the existing 630 area code and was implemented in 2007 to accommodate the increasing demand for phone numbers in DuPage, Cook, Kane, and Will counties.

When did area code 331 become effective?

Area code 331 was activated on October 7, 2007. It serves as an overlay to area code 630, which was itself created in 1996 from a split of area code 708. This overlay was necessary to meet the growing demand for phone numbers in the region.

How to dial a 331 number from a 630 number?

Ten-digit dialing is required for all calls within area codes 331 and 630. This means you must dial both the area code and the seven-digit phone number, even for local calls.

Why does Chicago have multiple area codes?

Chicago's multiple area codes, such as 331 and 630, are due to population growth. As the demand for phone numbers increases, new area codes (like 331) are added as overlays to existing ones (like 630) to ensure sufficient numbering resources are available.

What cities are covered by area code 331?

Area code 331 covers many cities in Chicago's western suburbs including Addison, North Aurora, Bartlett, Batavia, Bensenville, Bloomingdale, Bolingbrook, and many others. This area code encompasses parts of DuPage, Cook, Kane, and Will counties.

Who regulates area code 331 in Illinois?

Area code 331 is regulated by the Illinois Commerce Commission (ICC). The ICC oversees telecommunications services within Illinois, ensuring compliance with state regulations.

What is the North American Numbering Plan Administration?

The North American Numbering Plan Administration (NANPA) manages numbering resources for the North American Numbering Plan, ensuring compliance with national guidelines and managing area code assignments.

What major telecom carriers support area code 331?

Major telecom carriers such as AT&T, Verizon, T-Mobile, and Sprint provide service within area code 331. These carriers offer various services, including landline, wireless, and VoIP options.

Can I port my number to area code 331?

Porting your number to area code 331 is typically possible, depending on available numbers and carrier policies. Contact your desired telecom provider to inquire about porting options and procedures.

What is an area code overlay and how does it work?

An area code overlay, like 331 over 630, is a new area code introduced within the same geographic region as an existing one. It serves to provide additional phone numbers without requiring existing numbers to change and uses ten-digit dialing.

When should I use 1 before dialing a 331 number?

You should always use 1 before dialing a 331 number if you're calling from outside the 331 or 630 area codes. If you are within the 331/630 overlay area, you must use 1 plus the area code plus the number. Ten-digit dialing is mandatory within the 331/630 area.

How to find more information about Illinois area codes?

For further information about Illinois area codes, visit the websites of the Illinois Commerce Commission (ICC) or the North American Numbering Plan Administration (NANPA). These resources offer detailed information on area code assignments, regulations, and telecom services.