Establish a DuPage County presence with a 331 virtual number — Argonne National Laboratory's DOE research campus, Naperville's high-quality-of-life technology corridor, and Advocate Aurora Health's western suburbs clinical network. Activate in seconds.
Area code 331 is an overlay for DuPage and Kane counties in suburban Chicago, sharing geography with the original 630 area code across Naperville, Aurora, Elgin, Wheaton, Downers Grove, Schaumburg, and Lombard. Argonne National Laboratory in Lemont is one of the US Department of Energy's most important national laboratories, with particular strength in materials science, energy storage, and particle physics. McDonald's Corporation had its long-time global headquarters in Oak Brook (now relocated to Chicago's downtown, but retaining significant DuPage presence). Advocate Aurora Health and Central DuPage Hospital anchor the region's healthcare employment. Naperville consistently ranks among the highest-quality-of-life cities in the US.
From Chicago to Springfield 331 covers the Midwest region of Illinois.
Argonne National Laboratory in Lemont is one of the US's most important national laboratories, with particular strength in nuclear science, energy storage, and particle physics. Research technology, energy services, and defence contractors need a local 331 number to engage Argonne's significant research and procurement operations.
McDonald's global corporate campus in Oak Brook (now Chicago-based but retaining major DuPage operations) employs thousands in one of the region's most significant corporate headquarters. Food technology, franchise services, and professional services firms benefit from a 331 presence in DuPage County.
Naperville consistently ranks among the best cities in the US for quality of life, business climate, and education, attracting significant corporate and technology investment. Technology, professional services, and consumer companies benefit from a 331 number when engaging Naperville's affluent and well-educated market.
Advocate Aurora Health's network of hospitals and clinics in DuPage County makes it the region's largest healthcare employer. Healthcare technology and clinical services vendors need a local 331 number to engage Advocate Aurora's extensive western suburbs procurement network.
Every 331 number includes fourteen professional tools for DuPage County's research-and-corporate economy — compliance call recording for Argonne National Laboratory's vendor requirements, IVR for Advocate Aurora Health's clinical community, and analytics for Naperville's technology corridor and DuPage County's affluent suburban business market.
Redirect every call to any device — mobile, desk phone, or laptop. Set rules by time, caller, or team.
Four steps. Five minutes. No technical setup, no hardware required.
Browse 331 numbers by Naperville, Aurora, Wheaton, Downers Grove, or Schaumburg prefix — or port your existing DuPage County number for free.
Select a plan for your DuPage County team — Argonne National Laboratory vendor, Advocate Aurora Health partner, or Naperville technology firm, every feature included.
Configure your 331 line with Central Time routing for Argonne's research schedule and Advocate Aurora's clinical operations calendar.
Take 331 calls anywhere — Argonne's research community, the Naperville technology corridor's network, and DuPage County's healthcare and corporate cluster all see a trusted local number.
Pick a region, then select any state to see every active area code with city coverage, time zones, and a number-picker shortcut.
Everything you need to know before getting a virtual 331 phone number. Our team is one click away for anything else.
Instantly — under 60 seconds. Pick your 331 number, choose a plan, and your number is live and receiving calls with no hardware or carrier delays.
The 331 area code was introduced in 1995 and serves the Midwest region of Illinois.
Yes. TKOS 331 numbers are 100% virtual — establish a Illinois presence from anywhere in the world. Calls, texts, and voicemails route to any device you choose.
Yes. Outbound calls from TKOS always display your 331 number on the recipient's caller ID — giving customers a familiar local Illinois number to call back.
Yes. Every TKOS 331 number supports two-way SMS and MMS. Send and receive texts from the web dashboard, mobile app, or desktop — using the same 331 number your customers already know.
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