Phone numbers in Frederick, Maryland
Frederick has 88 phone prefixes in area codes 227, 240, 301.
Biggest holders: Verizon (local phone), Verizon Wireless, Onvoy. This is the local calling area (rate center) where those prefixes were first assigned.
- Mobile carrier 39%
- Local phone company 33%
- Internet / business phone carrier 26%
- Phone company 2%
Every prefix in Frederick
Search the first six digits of a number in this list. If it's here, the number started in Frederick with the carrier shown. If it isn't, check the Maryland page or look the number up.
| Prefix | Carrier | Type | Assigned |
|---|---|---|---|
| 227-203 | MCImetro (Verizon Business) | Internet / business phone carrier | 2023 |
| 227-223 | Commio | Internet / business phone carrier | 2023 |
| 227-226 | Onvoy | Internet / business phone carrier | 2024 |
| 227-253 | Onvoy | Internet / business phone carrier | 2024 |
| 227-281 | Verizon Wireless | Mobile carrier | 2025 |
| 227-317 | Onvoy | Internet / business phone carrier | 2026 |
| 227-666 | Onvoy | Internet / business phone carrier | 2025 |
| 227-800 | Onvoy | Internet / business phone carrier | 2024 |
| 240-215 | Level 3 (Lumen) | Internet / business phone carrier | – |
| 240-225 | Core Communications | Internet / business phone carrier | – |
| 240-236 | Verizon (local phone) | Local phone company | – |
| 240-285 | Verizon Wireless | Mobile carrier | – |
| 240-315 | Verizon (local phone) | Local phone company | – |
| 240-344 | AT&T Mobility | Mobile carrier | 2002 |
| 240-357 | Verizon Wireless | Mobile carrier | 2006 |
| 240-367 | T-Mobile (including Sprint) | Mobile carrier | 2002 |
| 240-379 | Verizon (local phone) | Local phone company | – |
| 240-397 | Verizon Wireless | Mobile carrier | 2009 |
| 240-405 | Windstream (PAETEC) | Internet / business phone carrier | 2004 |
| 240-409 | AT&T Mobility | Mobile carrier | – |
| 240-415 | Ymax Communications | Phone company | 2008 |
| 240-422 | T-Mobile (including Sprint) | Mobile carrier | 2002 |
| 240-439 | Verizon Wireless | Mobile carrier | 2008 |
| 240-440 | AT&T Mobility | Mobile carrier | 2009 |
| 240-446 | Verizon Wireless | Mobile carrier | 2001 |
| 240-457 | Verizon Wireless | Mobile carrier | 2008 |
| 240-529 | Verizon (local phone) | Local phone company | – |
| 240-549 | Verizon Wireless | Mobile carrier | 2016 |
| 240-566 | Verizon (local phone) | Local phone company | 2002 |
| 240-575 | Level 3 (Lumen) | Internet / business phone carrier | 2005 |
| 240-578 | Verizon Wireless | Mobile carrier | 2011 |
| 240-586 | Verizon (local phone) | Local phone company | 2006 |
| 240-608 | Nuso | Internet / business phone carrier | 2013 |
| 240-626 | T-Mobile (including Sprint) | Mobile carrier | – |
| 240-629 | Verizon (local phone) | Local phone company | – |
| 240-651 | Verizon Wireless | Mobile carrier | – |
| 240-656 | AT&T Mobility | Mobile carrier | 2019 |
| 240-674 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 240-680 | Peerless Network Of Maryland | Internet / business phone carrier | 2018 |
| 240-710 | MCImetro (Verizon Business) | Internet / business phone carrier | 2019 |
| 240-739 | IP Horizon | Internet / business phone carrier | 2020 |
| 240-741 | Airespring | Phone company | 2020 |
| 240-772 | Verizon Wireless | Mobile carrier | 2011 |
| 240-792 | T-Mobile (including Sprint) | Mobile carrier | 2021 |
| 240-815 | Verizon Wireless | Mobile carrier | 2015 |
| 240-831 | Onvoy | Internet / business phone carrier | 2016 |
| 240-840 | Onvoy | Internet / business phone carrier | 2018 |
| 240-877 | Onvoy | Internet / business phone carrier | 2016 |
| 240-910 | Onvoy | Internet / business phone carrier | 2021 |
| 240-931 | Nuso | Internet / business phone carrier | – |
| 240-971 | CenturyLink / Lumen | Local phone company | 2016 |
| 301-228 | Verizon (local phone) | Local phone company | – |
| 301-305 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 301-360 | Verizon (local phone) | Local phone company | – |
| 301-378 | Comcast | Internet / business phone carrier | 2007 |
| 301-401 | AT&T Mobility | Mobile carrier | – |
| 301-418 | Verizon (local phone) | Local phone company | 2002 |
| 301-471 | Verizon Wireless | Mobile carrier | – |
| 301-473 | Verizon (local phone) | Local phone company | – |
| 301-514 | Verizon Wireless | Mobile carrier | – |
| 301-524 | T-Mobile (including Sprint) | Mobile carrier | – |
| 301-600 | Verizon (local phone) | Local phone company | 2006 |
| 301-606 | Verizon Wireless | Mobile carrier | – |
| 301-619 | Verizon (local phone) | Local phone company | – |
| 301-620 | Verizon (local phone) | Local phone company | – |
| 301-624 | Verizon (local phone) | Local phone company | – |
| 301-631 | Verizon (local phone) | Local phone company | – |
| 301-639 | Verizon Wireless | Mobile carrier | – |
| 301-644 | Verizon (local phone) | Local phone company | – |
| 301-662 | Verizon (local phone) | Local phone company | – |
| 301-663 | Verizon (local phone) | Local phone company | – |
| 301-668 | Verizon (local phone) | Local phone company | – |
| 301-673 | AT&T Mobility | Mobile carrier | – |
| 301-676 | AT&T Mobility | Mobile carrier | – |
| 301-682 | Verizon (local phone) | Local phone company | – |
| 301-693 | T-Mobile (including Sprint) | Mobile carrier | – |
| 301-694 | Verizon (local phone) | Local phone company | – |
| 301-695 | Verizon (local phone) | Local phone company | – |
| 301-696 | Verizon (local phone) | Local phone company | – |
| 301-698 | Verizon (local phone) | Local phone company | – |
| 301-712 | MCImetro (Verizon Business) | Internet / business phone carrier | – |
| 301-732 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 301-748 | MetroPCS (T-Mobile) | Mobile carrier | – |
| 301-788 | Verizon Wireless | Mobile carrier | – |
| 301-815 | Verizon (local phone) | Local phone company | – |
| 301-835 | Vonage America | Internet / business phone carrier | 2018 |
| 301-846 | Verizon (local phone) | Local phone company | – |
| 301-898 | 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.