| District of Maryland area codes: 240 | |
|---|---|
| Country | United States |
| State/Province | Maryland |
| Major City | Baltimore |
| Time Zone | Eastern |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 240-372 | Montgomery | Gaithersburg, MD | Sprint Spectrum L.p. |
| 240-373 | Anne Arundel | Odenton, MD | Verizon Maryland |
| 240-374 | Prince Georges | Laurel, MD | Global Crossing Local Services-md |
| 240-375 | Prince Georges | Capitol Heights, MD | Sprint Spectrum L.p. |
| 240-376 | Charles | Hughesville, MD | Peerless Network Of Maryland |
| 240-377 | Charles | Indian Head, MD | Global Crossing Local Services-md |
| 240-378 | Allegany | Cumberland, MD | Core Communications |
| 240-379 | Frederick | Frederick, MD | Verizon Maryland |
| 240-380 | Montgomery | Cabin John, MD | Cellco Partnership DBA Verizon Wireless |
| 240-381 | Montgomery | Silver Spring, MD | New Cingular Wireless PCS - DC |
| 240-382 | Washington | Hagerstown, MD | Teleport Communications America |
| 240-383 | Montgomery | Chevy Chase, MD | New Cingular Wireless PCS - DC |
| 240-384 | Saint Marys | Callaway, MD | Peerless Network Of Maryland |
| 240-385 | Frederick | Myersville, MD | Verizon Maryland |
| 240-386 | Montgomery | Gaithersburg, MD | Verizon Maryland |
| 240-387 | Montgomery | Chevy Chase, MD | Cavalier East LLC |
| 240-388 | Montgomery | Gaithersburg, MD | Sprint Spectrum L.p. |
| 240-389 | Montgomery | Sandy Spring, MD | Atx Telecommunications Services, Ltd |
| 240-390 | Montgomery | Sandy Spring, MD | Cavalier Telephone Mid-atlantic |
| 240-391 | Prince Georges | Mount Rainier, MD | Global Crossing Local Services-md |
There are 522 prefixes, In the code area, the major cities are Aspen Hill, MD;Bethesda, MD;Bowie, MD;Chillum, MD;. The major city is Baltimore.