| General Information about Area Code 240 | |
|---|---|
| Country | United States |
| State / Province / Territory | Maryland |
| Major City | Gaithersburg |
| Time Zone | Eastern (UTC-05:00) |
| Prefix | Primary City | County | Phone Type |
|---|---|---|---|
| 240-268 | Rockville | Montgomery | Landline |
| 240-682 | Waldorf | Charles | Landline |
| 240-601 | Laurel | Prince Georges | Wireless |
| 240-380 | Glen Echo | Montgomery | Wireless |
| 240-764 | Bethesda | Montgomery | Landline |
| 240-823 | Brandywine | Prince Georges | Landline |
| 240-518 | Waldorf | Charles | Wireless |
| 240-868 | Brentwood | Prince Georges | Landline |
| 240-223 | Brentwood | Prince Georges | Landline |
| 240-514 | Glen Echo | Montgomery | Landline |
| 240-517 | Columbia | Howard | Wireless |
| 240-298 | Leonardtown | Saint Marys | Wireless |
| 240-925 | Leonardtown | Saint Marys | Wireless |
| 240-239 | Leonardtown | Saint Marys | Landline |
| 240-250 | Brandywine | Prince Georges | Landline |
| 240-426 | Chevy Chase | Montgomery | Wireless |
| 240-538 | Leonardtown | Saint Marys | Landline |
| 240-266 | Brentwood | Prince Georges | Landline |
| 240-841 | Laurel | Howard | Landline |
| 240-559 | Ashton | Montgomery | Landline |