Phone numbers in Gaithersburg, Maryland
Gaithersburg has 80 phone prefixes in area codes 227, 240, 301.
Biggest holders: Verizon (local phone), Onvoy, MCImetro (Verizon Business). This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 22%
- Local phone company 31%
- Internet / business phone carrier 41%
- Phone company 5%
Every prefix in Gaithersburg
Search the first six digits of a number in this list. If it's here, the number started in Gaithersburg with the carrier shown. If it isn't, check the Maryland page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 227-227 | Onvoy | Internet / business phone carrier | 2024 |
| 227-245 | Onvoy | Internet / business phone carrier | 2024 |
| 227-258 | AT&T Mobility | Mobile carrier | 2024 |
| 227-277 | T-Mobile (including Sprint) | Mobile carrier | 2025 |
| 227-324 | AT&T Mobility | Mobile carrier | 2026 |
| 227-500 | Opentact | Phone company | 2026 |
| 227-529 | Onvoy | Internet / business phone carrier | 2025 |
| 240-224 | Verizon Wireless | Mobile carrier | 2012 |
| 240-243 | MCImetro (Verizon Business) | Internet / business phone carrier | – |
| 240-246 | Starpower Communications | Phone company | – |
| 240-252 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 240-261 | Onvoy | Internet / business phone carrier | 2015 |
| 240-306 | MCImetro (Verizon Business) | Internet / business phone carrier | – |
| 240-327 | Core Communications | Internet / business phone carrier | – |
| 240-361 | Windstream (PAETEC) | Internet / business phone carrier | – |
| 240-364 | Windstream (PAETEC) | Internet / business phone carrier | 2001 |
| 240-372 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 240-388 | MetroPCS (T-Mobile) | Mobile carrier | 2002 |
| 240-404 | MCImetro (Verizon Business) | Internet / business phone carrier | 2001 |
| 240-449 | AT&T Mobility | Mobile carrier | – |
| 240-454 | Windstream (PAETEC) | Internet / business phone carrier | 2005 |
| 240-474 | Baltimore-washington Telephone (bwt) | Phone company | 2015 |
| 240-477 | Windstream (PAETEC) | Internet / business phone carrier | 2005 |
| 240-562 | MCImetro (Verizon Business) | Internet / business phone carrier | 2015 |
| 240-597 | Peerless Network Of Maryland | Internet / business phone carrier | – |
| 240-631 | Verizon (local phone) | Local phone company | – |
| 240-632 | Verizon (local phone) | Local phone company | – |
| 240-654 | AT&T Mobility | Mobile carrier | 2006 |
| 240-658 | Vonage America | Internet / business phone carrier | 2018 |
| 240-683 | Verizon (local phone) | Local phone company | – |
| 240-686 | Verizon (local phone) | Local phone company | – |
| 240-690 | Teleport Communications America | Internet / business phone carrier | 2016 |
| 240-702 | Verizon Wireless | Mobile carrier | 2014 |
| 240-720 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 240-750 | AT&T Mobility | Mobile carrier | 2005 |
| 240-751 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 240-780 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 240-793 | MetroPCS (T-Mobile) | Mobile carrier | 2001 |
| 240-798 | Onvoy | Internet / business phone carrier | 2021 |
| 240-801 | Verizon Wireless | Mobile carrier | 2013 |
| 240-805 | Verizon Wireless | Mobile carrier | 2015 |
| 240-813 | Windstream (PAETEC) | Internet / business phone carrier | – |
| 240-848 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 240-912 | Windstream (PAETEC) | Internet / business phone carrier | – |
| 240-937 | Bandwidth | Internet / business phone carrier | 2022 |
| 240-981 | Nuso | Internet / business phone carrier | 2023 |
| 240-982 | Onvoy | Internet / business phone carrier | 2023 |
| 301-208 | Verizon (local phone) | Local phone company | – |
| 301-216 | Verizon (local phone) | Local phone company | – |
| 301-250 | MCImetro (Verizon Business) | Internet / business phone carrier | – |
| 301-252 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 301-301 | Onvoy | Internet / business phone carrier | 2022 |
| 301-330 | Verizon (local phone) | Local phone company | – |
| 301-337 | MCImetro (Verizon Business) | Internet / business phone carrier | – |
| 301-355 | Verizon (local phone) | Local phone company | 2005 |
| 301-366 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 301-370 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 301-407 | Verizon (local phone) | Local phone company | – |
| 301-515 | Verizon (local phone) | Local phone company | – |
| 301-519 | Verizon (local phone) | Local phone company | – |
| 301-525 | Quantum Telecommunications | Phone company | 2003 |
| 301-527 | Verizon (local phone) | Local phone company | – |
| 301-528 | Verizon (local phone) | Local phone company | – |
| 301-540 | Verizon (local phone) | Local phone company | – |
| 301-556 | Teleport Communications America | Internet / business phone carrier | – |
| 301-569 | Verizon Wireless | Mobile carrier | – |
| 301-591 | Windstream (PAETEC) | Internet / business phone carrier | – |
| 301-740 | Verizon (local phone) | Local phone company | 2004 |
| 301-820 | Teleport Communications America | Internet / business phone carrier | – |
| 301-869 | Verizon (local phone) | Local phone company | – |
| 301-916 | Verizon (local phone) | Local phone company | – |
| 301-926 | Verizon (local phone) | Local phone company | – |
| 301-944 | MCImetro (Verizon Business) | Internet / business phone carrier | – |
| 301-947 | Verizon (local phone) | Local phone company | – |
| 301-956 | Verizon (local phone) | Local phone company | 2002 |
| 301-963 | Verizon (local phone) | Local phone company | – |
| 301-972 | Verizon (local phone) | Local phone company | – |
| 301-977 | Verizon (local phone) | Local phone company | – |
| 301-987 | Verizon (local phone) | Local phone company | – |
| 301-990 | Verizon (local phone) | Local phone company | – |
Most prefixes are pooled: the 10,000 numbers in each are handed out in blocks of 1,000 to different carriers, and people can also take their numbers to another carrier. So the carrier shown is where the prefix started, not a guarantee about any one number. Source: NANPA central office code records, 2026-10-10.