| District of Maryland area codes: 240 | |
|---|---|
| Country | United States |
| State/Province | Maryland |
| Major City | Baltimore |
| Time Zone | Eastern |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 240-269 | Prince Georges | Mount Rainier, MD | Peerless Network Of Maryland |
| 240-270 | Charles | Waldorf, MD | Cellco Partnership DBA Verizon Wireless |
| 240-271 | Montgomery | Bethesda, MD | New Cingular Wireless PCS - DC |
| 240-272 | Montgomery | Bethesda, MD | Sprint Spectrum L.p. |
| 240-273 | Prince Georges | Mount Rainier, MD | Broadwing Communications. LLC |
| 240-274 | Montgomery | Bethesda, MD | New Cingular Wireless PCS - DC |
| 240-275 | Garrett | Grantsville, MD | Core Communications |
| 240-276 | Montgomery | Rockville, MD | Verizon Maryland |
| 240-277 | Montgomery | Bethesda, MD | Sprint Spectrum L.p. |
| 240-278 | Prince Georges | Laurel, MD | Cellco Partnership DBA Verizon Wireless |
| 240-279 | Charles | Waldorf, MD | Core Communications |
| 240-280 | Prince Georges | Laurel, MD | Comcast Phone Of Northern Maryland |
| 240-281 | Montgomery | Bethesda, MD | New Cingular Wireless PCS - DC |
| 240-282 | Saint Marys | Mechanicsville, MD | Peerless Network Of Maryland |
| 240-283 | Montgomery | Kensington, MD | Paetec Communications |
| 240-284 | Allegany | Frostburg, MD | Level 3 Communications |
| 240-285 | Frederick | Frederick, MD | Cellco Partnership DBA Verizon Wireless |
| 240-286 | Montgomery | Bethesda, MD | Sprint Spectrum L.p. |
| 240-287 | Washington | Hancock, MD | Core Communications |
| 240-288 | Frederick | Thurmont, MD | Comcast Phone Of Northern Maryland |
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.