Area code 240: where it is and who calls from it
Area code 240 is in Maryland.
Western Maryland (Silver Spring; Washington, D.C., suburbs; all counties which touch the Potomac River; Waldorf, Hagerstown, Frederick, Rockville, Cumberland)
| Where | Maryland |
|---|---|
| Time zone | Eastern Time ยท local time |
| In service since | 1997 |
| Overlay | Yes, with 227, 301 |
| Prefixes assigned | 785 of 792 possible (99%) |
Overlay: 240 covers the same area as 227, 301. Overlay areas use 10-digit dialing, so a seven-digit number alone won't connect, and neighbors can have different area codes.
Where 240 numbers started
Every prefix is assigned to a rate center, the local calling area it was set up in. These are the biggest in 240, with how many prefixes each has.
Who holds 240 numbers
- Mobile carrier 38%
- Local phone company 7%
- Internet / business phone carrier 51%
- Phone company 4%
| Carrier | Type | Prefixes | Share |
|---|---|---|---|
| T-Mobile (including Sprint) | Mobile carrier | 117 | 15% |
| Verizon Wireless | Mobile carrier | 85 | 11% |
| AT&T Mobility | Mobile carrier | 69 | 9% |
| Windstream (PAETEC) | Internet / business phone carrier | 63 | 8% |
| Onvoy | Internet / business phone carrier | 62 | 8% |
| Level 3 (Lumen) | Internet / business phone carrier | 62 | 8% |
| MCImetro (Verizon Business) | Internet / business phone carrier | 49 | 6% |
| Verizon (local phone) | Local phone company | 48 | 6% |
| Peerless Network Of Maryland | Internet / business phone carrier | 42 | 5% |
| Bandwidth | Internet / business phone carrier | 35 | 4% |
Most prefixes are pooled: the 10,000 numbers in each are handed out in blocks of 1,000 to different carriers, and people can also take their numbers to another carrier. So the carrier shown is where the prefix started, not a guarantee about any one number.
States served: Maryland.
Other area codes in Maryland
Got a call from 240?
An area code tells you where a number was first assigned, not where the caller is. People keep their numbers when they move, and scammers can fake any number. If you weren't expecting the call, let it go to voicemail.
If the call shows a 240 number that matches the first six digits of your own, that's often neighbor spoofing. Use the box above to check the full number.
Area code facts from the NANPA area code database (updated 10/06/2026); prefixes and carriers from NANPA's central office code records (updated 2026-10-10). Place description adapted from Wikipedia, CC BY-SA 4.0.