| 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 |
|---|---|---|---|
| 240-606 | Laurel | Prince Georges | Wireless |
| 240-763 | - | - | - |
| 240-566 | Frederick | Frederick | Landline |
| 240-424 | Brentwood | Prince Georges | Wireless |
| 240-667 | Brentwood | Prince Georges | Landline |
| 240-386 | Gaithersburg | Montgomery | Landline |
| 240-929 | Brentwood | Prince Georges | Landline |
| 240-806 | Charles | Charles | - |
| 240-714 | Brentwood | Prince Georges | Wireless |
| 240-330 | Glen Echo | Montgomery | Wireless |
| 240-377 | Indian Head | Charles | Landline |
| 240-446 | Frederick | Frederick | Wireless |
| 240-350 | Laurel | Prince Georges | Wireless |
| 240-323 | Emmitsburg | Frederick | Landline |
| 240-499 | Glen Echo | Montgomery | Landline |
| 240-312 | District Heights | Prince Georges | Landline |
| 240-605 | Laurel | Prince Georges | Wireless |
| 240-217 | Hagerstown | Washington | Wireless |
| 240-283 | Silver Spring | Montgomery | Landline |
| 240-654 | Gaithersburg | Montgomery | Wireless |