| 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 |
|---|---|---|---|
| 240-208 | Port Tobacco | Charles | Landline |
| 240-765 | Bethesda | Montgomery | Landline |
| 240-320 | Waldorf | Charles | Landline |
| 240-883 | Ashton | Montgomery | Landline |
| 240-547 | Laurel | Howard | Landline |
| 240-359 | Indian Head | Charles | Landline |
| 240-234 | Brentwood | Prince Georges | Wireless |
| 240-864 | Rockville | Montgomery | Landline |
| 240-222 | Waldorf | Charles | Landline |
| 240-619 | Bethesda | Montgomery | Landline |
| 240-465 | Brentwood | Prince Georges | Landline |
| 240-374 | Laurel | Howard | Landline |
| 240-262 | Great Mills | Saint Marys | Wireless |
| 240-352 | Port Tobacco | Charles | Landline |
| 240-812 | Poolesville | Montgomery | Landline |
| 240-672 | Rockville | Montgomery | Landline |
| 240-379 | Frederick | Frederick | Landline |
| 240-525 | Upper Marlboro | Prince Georges | Landline |
| 240-781 | - | - | - |
| 240-466 | Charlotte Hall | Saint Marys | Wireless |