| 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 |
|---|---|---|---|
| 240-523 | Port Tobacco | Charles | Landline |
| 240-322 | Westernport | Allegany | Landline |
| 240-626 | Frederick | Frederick | Wireless |
| 240-542 | Greenbelt | Prince Georges | Landline |
| 240-469 | Hagerstown | Washington | Wireless |
| 240-376 | Hughesville | Charles | Landline |
| 240-232 | Brentwood | Prince Georges | Landline |
| 240-775 | - | - | - |
| 240-297 | Greenbelt | Prince Georges | Landline |
| 240-488 | Oakland | Garrett | Landline |
| 240-782 | Clarksburg | Montgomery | Landline |
| 240-979 | Cumberland | Allegany | Landline |
| 240-609 | Cumberland | Allegany | Wireless |
| 240-704 | Brentwood | Prince Georges | Wireless |
| 240-760 | - | - | - |
| 240-212 | Oakland | Garrett | Landline |
| 240-767 | District Heights | Prince Georges | Landline |
| 240-751 | Gaithersburg | Montgomery | Landline |
| 240-253 | Cheltenham | Prince Georges | Landline |
| 240-683 | Gaithersburg | Montgomery | Landline |