| District of Maryland area codes: 301 | |
|---|---|
| Country | United States |
| State/Province | Maryland |
| Major City | Baltimore |
| Time Zone | Eastern (UTC-05:00) |
| Prefix | County | Primary City | Company |
|---|---|---|---|
| 301-222 | Montgomery | Bethesda, MD | Cavalier Telephone Mid-atlantic |
| 301-223 | Washington | Williamsport, MD | Verizon Maryland |
| 301-224 | Montgomery | Chevy Chase, MD | Usa Mobility Wireless |
| 301-225 | Prince Georges | Glenn Dale, MD | Teleport Communications America - DC |
| 301-226 | Prince Georges | Hyattsville, MD | Verizon Maryland |
| 301-227 | Montgomery | Glen Echo, MD | Verizon Maryland |
| 301-228 | Frederick | Frederick, MD | Verizon Maryland |
| 301-229 | Montgomery | Glen Echo, MD | Verizon Maryland |
| 301-230 | Montgomery | Rockville, MD | Verizon Maryland |
| 301-231 | Montgomery | Rockville, MD | Verizon Maryland |
| 301-232 | Montgomery | Sandy Spring, MD | Mci Worldcom Communications |
| 301-233 | Montgomery | Silver Spring, MD | Cellco Partnership DBA Verizon Wireless |
| 301-234 | Prince Georges | Fort Washington, MD | Verizon Maryland |
| 301-235 | Prince Georges | Clinton, MD | Mcimetro Access Transmission Services LLC |
| 301-236 | Montgomery | Silver Spring, MD | Verizon Maryland |
| 301-237 | Prince Georges | Beltsville, MD | Sprint Spectrum L.p. |
| 301-238 | Prince Georges | Temple Hills, MD | Verizon Maryland |
| 301-239 | Prince Georges | Hyattsville, MD | Verizon Maryland |
| 301-240 | Montgomery | Gaithersburg, MD | Verizon Maryland |
| 301-241 | Washington | Highfield, MD | Verizon Maryland |
There are 775 prefixes, In the code area, the major cities are Aspen Hill, MD;Bethesda, MD;Bowie, MD;Chillum, MD;. The major city is Baltimore.