301
Area code
MD
United States geographic area code, in service since 1947-01-01. Part of the 240/227/301 overlay complex — ten-digit dialing required.
Statusin service
Introduced1947-01-01
JurisdictionMD, US
Local dialing10D
Time zoneEastern
Last verified2026-09-17
Utilization 101% of assignable prefixes assigned
As of 09/17/2026
0%800 of ~792 assignable NXX values (200–999 excl. N11)100%
Prefix-level assignment does not equal number-level exhaustion; thousands-block pooling extends capacity. First assignment on record 2002-01-09, most recent 2025-07-01.
Area codes serve rate-center geographies, not municipal boundaries. “MD” identifies the jurisdiction, not an exact city footprint.
Top assignees
Ranked by assigned prefixes · initial assignee ≠ current carrier| Rank | Assignee | Prefixes | Share |
|---|---|---|---|
| 01 | VERIZON MARYLAND, INC. | 465 | 58.1% |
| 02 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MD | 51 | 6.4% |
| 03 | NEW CINGULAR WIRELESS PCS, LLC - DC | 47 | 5.9% |
| 04 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 40 | 5% |
| 05 | TELEPORT COMMUNICATIONS AMERICA, LLC - DC | 31 | 3.9% |
| 06 | OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC | 31 | 3.9% |
| 07 | LEVEL 3 COMMUNICATIONS, LLC - MD | 15 | 1.9% |
| 08 | METROPCS, INC. | 14 | 1.8% |
| 09 | COMCAST IP PHONE, LLC | 12 | 1.5% |
| 10 | BANDWIDTH.COM CLEC, LLC - MD | 11 | 1.4% |
Important: these are initial assignees from NANPA CO-code records — the carrier a prefix was originally assigned to. Because of number portability, the current serving carrier of any individual number may differ.
Change history
Recorded events for this NPA- 1947-01-01Area code 301 entered service.
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2022-09-27 | PL-603 ↗ | NPA 227 to Overlay NPA 240/301 (Maryland) |
| 1996-06-21 | IL-96-06-009 ↗ | NANP-Overlay of 301 (Maryland) Numbering Plan Area (NPA) |