| 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 |
|---|---|---|---|
| 301-304 | Frederick | Frederick, MD | Comcast Phone Of Northern Maryland |
| 301-305 | Frederick | Frederick, MD | Sprint Spectrum L.p. |
| 301-306 | Prince Georges | Lanham, MD | Verizon Maryland |
| 301-307 | Prince Georges | College Park, MD | Verizon Maryland |
| 301-308 | Prince Georges | Greenbelt, MD | Usa Mobility Wireless |
| 301-309 | Montgomery | Rockville, MD | Verizon Maryland |
| 301-310 | Howard | Columbia, MD | Verizon Maryland |
| 301-312 | Prince Georges | Oxon Hill, MD | New Cingular Wireless PCS - DC |
| 301-313 | Prince Georges | Greenbelt, MD | Verizon Maryland |
| 301-314 | Prince Georges | Hyattsville, MD | Paetec Communications |
| 301-315 | Montgomery | Rockville, MD | Verizon Maryland |
| 301-316 | Prince Georges | Temple Hills, MD | Verizon Maryland |
| 301-317 | Prince Georges | Laurel, MD | Verizon Maryland |
| 301-318 | Montgomery | Bethesda, MD | New Cingular Wireless PCS - DC |
| 301-319 | Montgomery | Rockville, MD | Verizon Maryland |
| 301-320 | Montgomery | Glen Echo, MD | Verizon Maryland |
| 301-321 | Montgomery | Rockville, MD | Telcove Operations |
| 301-322 | Prince Georges | Hyattsville, MD | Verizon Maryland |
| 301-323 | Prince Georges | Laurel, MD | Tw Telecom Of Maryland LLC |
| 301-324 | Prince Georges | Capitol Heights, 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.