Skip to content
Country Dialing CodesA clearer way to call the world
AboutContact
Español — prefijos-telefonicos.comFrançais — indicatifs-telephoniques.net
US area code · Maryland

240 area code

Where the 240 area code is, its overlay and how to dial a +1 240 number from anywhere.

CoversAspen Hill, MarylandTime zoneEastern (ET)TypeOverlay
Quick answer

The 240 area code is in Aspen Hill, Maryland, United States (Eastern (ET)). To call from abroad: +1 240 555-0123. It is an overlay, so all 10 digits are dialled.

StateMaryland
Main areaAspen Hill
Time zoneEastern (ET)
TypeOverlay
10-digit dialingRequired
In service since21-Jun-1996

The 240 area code is a geographic North American Numbering Plan (NANP) code covering Aspen Hill, Maryland. It has been in service since 21-Jun-1996 and sits in the Eastern (ET) time zone.

Overlay 240 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.

240227301

How to dial a 240 number

From abroad+1 240 555-0123
Within the US / Canada1 240 555-0123
Locally (same area)240 555-0123

Cities in the 240 area code

A 240 number is usually in one of these places in Maryland — 6 counties.

Aspen HillBowie Prince GeorgesChillumClinton Prince GeorgesCollege Park Prince GeorgesCumberland AlleganyFairlandFort Washington Prince GeorgesFrederick FrederickGaithersburg MontgomeryGermantown MontgomeryGreenbelt Prince GeorgesHagerstown WashingtonLandoverMontgomery Village MontgomeryNorth BethesdaNorth PotomacOlney MontgomeryPotomac MontgomeryRockville MontgomerySaint CharlesSilver Spring MontgomerySouth LaurelSuitland Prince GeorgesWaldorf CharlesWhite Oak

Other Maryland area codes

227301410443667

Frequently asked questions

Where is the 240 area code?

The 240 area code is in Aspen Hill, Maryland, United States (Eastern (ET)).

Is 240 an overlay area code?

Yes. 240 overlays the same region as 227, 301, so callers dial all 10 digits.

Do I have to dial 10 digits for 240?

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

How do I call a 240 number from another country?

Dial your exit code (or +), then 1, then 240, then the number: +1 240 555-0123.

Source: NANPA numbering plan. An area code covers a region, not a precise address — a 240 number does not pinpoint a street or ZIP code.

Number holders in area code 240

Each prefix (the three digits after the area code) is assigned by NANPA to one telephone company. 800 prefixes are in use in 240, shared by 47 companies. The largest holders:

CompanyPrefixesShare
Omnipoint Communications Cap Operations, LLC11715%
Cellco Partnership Dba Verizon Wireless8511%
New Cingular Wireless PCS, LLC699%
Paetec Itel, LLC638%
Level 3 Communications, LLC597%
Onvoy, LLC567%

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

Complaints about 240 numbers

Reports to the FTC, last 30 days
590
Recorded messages or robocalls
59%
Rank among area codes
#142 of 670
Most reported subjects
Other (217)
Reducing your debt (credit cards, mortgage, student loans) (112)
Calls pretending to be government, businesses, or family and friends (94)

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 240 — cities & rate centres

Explore by continent