NANP area code
301
UTC−5, UTC−4 during daylight saving
- State
- Maryland
- Primary city
- Baltimore
- Time zone
- Eastern
- In service
- 1947
NANP area code
301
UTC−5, UTC−4 during daylight saving
The code reaches 217 communities and 14 counties and independent cities across Maryland.
The area code itself carries no risk signal. 301 is assigned to Baltimore, Maryland, so a call from it is consistent with a real caller in that area — but the digits alone prove nothing, because they can be forged.
Caller ID is set by whoever places the call, not verified by the network. That is why neighbour spoofing works: an operation anywhere in the world can display a number that matches the area code — and often the first three digits after it — of the person being called, so the call looks local. Every community in the 301 territory is a plausible-looking origin for a forged 301 number, which is why one can be made to look like a neighbour to so many people. The same applies to its overlay codes 227 and 240, which serve the same ground.
If you did not recognise the call: let it go to voicemail — a legitimate caller with real business will leave one. Do not return the call using the number shown; look the organisation up independently and call the number you found. Never confirm personal details, card numbers, or one-time codes to someone who called you, however plausible the number looked.
Codes.zone publishes no complaint counts, risk scores, or caller identities. We hold no data on individual numbers and will not estimate what we cannot source.
Time there now
—
Eastern · UTC−5, UTC−4 during daylight saving
Reasonable callback window
8:00 AM – 9:00 PM
local time in Eastern
Federal rules bar telemarketing calls to a residence outside 8:00 AM–9:00 PM in the called party's own time zone. It is a sensible bound for a personal callback too — and a caller who rang you well outside it was not observing it.
301 does not have its territory to itself. 227 and 240 cover the same ground, serving Baltimore and the rest of the 301 territory. An overlay is what a regulator adds when a region runs out of assignable numbers: rather than splitting the area and forcing half the residents to change their number, a second code is laid over the top and new numbers are issued from it.
The practical consequence: two neighbours on the same street can hold numbers in different area codes, so the code tells you nothing about which part of town a caller is in — and local calls must be dialled as all ten digits, because seven is no longer unambiguous.
| City | ZIP codes | County or independent city |
|---|---|---|
| Baltimore | 42 | Anne Arundel County |
| Silver Spring | 16 | Montgomery County |
| Bethesda | 11 | Montgomery County |
| Gaithersburg | 9 | Montgomery County |
| Annapolis | 8 | Anne Arundel County |
| Rockville | 8 | Montgomery County |
| Bowie | 7 | Prince George's County |
| Hyattsville | 7 | Prince George's County |
| Laurel | 7 | Anne Arundel County |
| Frederick | 6 | Frederick County |
| Hagerstown | 6 | Washington County |
| Capitol Heights | 5 | Prince George's County |
| Cumberland | 5 | Allegany County |
| Upper Marlboro | 5 | Prince George's County |
| Waldorf | 4 | Charles County |
| College Park | 3 | Prince George's County |
| Columbia | 3 | Howard County |
| Ellicott City | 3 | Howard County |
| Germantown | 3 | Montgomery County |
| Greenbelt | 3 | Prince George's County |
197 further communities not listed. All Maryland area codes →
Scope every community matched to 301. Source geoinfo-dataset (full_dataset) ZIP→NPA (2018 snapshot), GeoNames US postal codes (2026-07 postal dump) and Census 2024 county Gazetteer (2024 Gazetteer). Updated . Coordinates are place reference points, not boundaries.
We do not publish the NXX prefixes inside 301. The assignment of prefixes to rate centres comes from LERG routing data, which is proprietary, and we will not estimate it from postal data — ZIP codes and telephone prefixes do not map onto each other. Awaiting a clean-rights NPA-NXX source.
301 has served this territory since 1947. It eventually ran short of exchanges to hand out, and rather than split the region and make half its residents change their number, the regulator laid 227 over the same ground in 2023 and 240 over the same ground in 1997. New lines here are issued from the newer code, which is why a neighbour’s number may not start with 301.