NumberResearch Membership · Data 09/19/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/19/2026

Full prefixes (NXX) Thousands-blocks (1,000-number pools)

The Code holder is who opened each NPA-NXX prefix — not necessarily who holds the numbers. A prefix is 10,000 numbers, but under pooling its ten 1,000-number blocks are handed out individually, often to different carriers; the code holder may hold only one block, or none. The Thousands-blocks column shows how the ten blocks are really split — click which blocks → to see who holds each 1,000-number block and its last-4-digit range. Assignments are initial assignments; the current serving carrier may differ due to portability.

Most active assignees, all time — NPA 301
VERIZON MARYLAND, INC. 465
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MD 51
NEW CINGULAR WIRELESS PCS, LLC - DC 47
MCIMETRO ACCESS TRANSMISSION SERVICES LLC 40
TELEPORT COMMUNICATIONS AMERICA, LLC - DC 31
New assignments by month Sep 2026 Aug 2026 Jul 2026 Jun 2026 May 2026 Apr 2026 Mar 2026 Feb 2026 Jan 2026 Dec 2025 Nov 2025 Oct 2025
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Recent NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
2025-07-01 301-558 0–9 XXXall 10 · 3 holders which blocks → OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 6855 WSNG236Z13 MD
2023-02-07 301-726 3XXX which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 KITZMILLER MD
2022-11-07 301-201 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 WSNGTNZN10 MD
2022-08-30 301-301 0–9 XXXwhole prefix which blocks → ONVOY, LLC - MD 876D GAITHERSBG MD
2022-07-27 301-635 0–9 XXXall 10 · 2 holders which blocks → BANDWIDTH.COM CLEC, LLC - MD 071F WSHNGTNZN5 MD
2022-07-26 301-550 0–9 XXXall 10 · 5 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 WSNGTNZN10 MD
2022-07-15 301-381 0–9 XXXwhole prefix which blocks → ONVOY, LLC - MD 876D WSHNGTNZN2 MD
2022-07-15 301-450 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 WSHNGTNZN3 MD
2022-05-05 301-410 0–9 XXXwhole prefix which blocks → ONVOY SPECTRUM, LLC 624H WSHNGTNZN6 MD
2022-05-04 301-781 0–9 XXXwhole prefix which blocks → ONVOY SPECTRUM, LLC 624H WSHNGTNZN4 MD
2022-01-24 301-597 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 WALDORF MD
2019-05-28 301-709 0–9 XXXall 10 · 3 holders which blocks → CSC WIRELESS, LLC 425J CUMBERLAND MD
2018-11-27 301-835 0–9 XXXall 10 · 9 holders which blocks → VONAGE AMERICA LLC 197D FREDERICK MD
2017-06-02 301-936 0–9 XXXall 10 · 3 holders which blocks → TELNYX LLC 073H HAGERSTOWN MD
2015-02-20 301-532 0–9 XXXall 10 · 3 holders which blocks → OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 6855 LAUREL238 MD
2015-02-18 301-900 0–9 XXXwhole prefix which blocks → ONVOY, LLC - MD 876D WSHNGTNZN2 MD
2014-11-11 301-269 0–9 XXXall 10 · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 WSHNGTNZN2 MD
2014-04-07 301-546 0–9 XXXwhole prefix which blocks → VERIZON MARYLAND, INC. 9212 WSHNGTNZN4 MD
2012-12-27 301-914 0–9 XXXall 10 · 2 holders which blocks → MOUNTAIN COMMUNICATIONS, LLC DBA PROCOM - MD 676A OAKLAND MD
2012-10-11 301-612 0–9 XXXall 10 · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - MD 7325 WSNG238Z14 MD
2011-10-04 301-267 0–9 XXXall 10 · 3 holders which blocks → OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 6855 WSHNGTNZN3 MD
2011-10-04 301-844 0–9 XXXall 10 · 8 holders which blocks → OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 6855 WSHNGTNZN3 MD
2011-09-06 301-557 0–9 XXXall 10 · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MD 6119 WSHNGTNZN3 MD
2011-02-24 301-200 0–9 XXXall 10 · 5 holders which blocks → BANDWIDTH.COM CLEC, LLC - MD 071F INDIANHEAD MD
2010-03-29 301-400 0–9 XXXwhole prefix which blocks → VERIZON MARYLAND, INC. 9212 WSHNGTNZN2 MD
2009-05-21 301-225 0–9 XXXwhole prefix which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - DC 7529 WSNG236Z14 MD
2008-12-19 301-202 0–9 XXXall 10 · 4 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 WSHNGTNZN2 MD
2007-05-23 301-690 0–9 XXXall 10 · 7 holders which blocks → IDT AMERICA, CORP. - MD 228C LEONARDTN MD
2007-03-30 301-300 0–9 XXXall 10 · 2 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MD 6395 WSHNGTNZN2 MD
2007-03-06 301-304 0–9 XXXall 10 · 3 holders which blocks → COMCAST IP PHONE, LLC 318J WALKERSVL MD
2007-03-06 301-969 0–9 XXXall 10 · 5 holders which blocks → COMCAST IP PHONE, LLC 318J BRUNSWICK MD
2007-02-20 301-378 0–9 XXXall 10 · 5 holders which blocks → COMCAST IP PHONE, LLC 318J FREDERICK MD
2006-11-15 301-534 0–9 XXXwhole prefix which blocks → YMAX COMMUNICATIONS CORP. - MD 281E INDIANHEAD MD
2006-10-12 301-357 0–9 XXXall 10 · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MD 6395 WSHNGTNZN3 MD
2006-08-16 301-363 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MD 6119 DAMASCS240 MD
2006-07-20 301-243 0–9 XXXwhole prefix which blocks → VERIZON MARYLAND, INC. 9212 WSHNGTNZN2 MD
2006-07-06 301-600 0–9 XXXwhole prefix which blocks → VERIZON MARYLAND, INC. 9212 FREDERICK MD
2006-06-21 301-328 0–9 XXXall 10 · 4 holders which blocks → COMCAST IP PHONE, LLC 318J WSHNGTNZN3 MD
2006-03-09 301-327 0–9 XXXall 10 · 5 holders which blocks → COMCAST IP PHONE, LLC 318J WSNG238Z15 MD
2006-01-31 301-338 0–9 XXXall 10 · 6 holders which blocks → IDT AMERICA, CORP. - MD 228C CUMBERLAND MD
2005-12-30 301-710 0–9 XXXall 10 · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MD 6119 WALDORF MD
2005-12-08 301-355 0–9 XXXall 10 · 5 holders which blocks → VERIZON MARYLAND, INC. 9212 GAITHERSBG MD
2005-03-11 301-892 0–9 XXXall 10 · 5 holders which blocks → VERIZON MARYLAND, INC. 9212 WSHNGTNZN4 MD
2004-10-05 301-302 0–9 XXXall 10 · 5 holders which blocks → METROPCS, INC. 5562 HAGERSTOWN MD
2004-04-22 301-740 0–9 XXXall 10 · 4 holders which blocks → VERIZON MARYLAND, INC. 9212 GAITHERSBG MD
2004-03-19 301-660 0–9 XXXall 10 · 2 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 KEEDYSVL MD
2004-03-18 301-750 0–9 XXXall 10 · 5 holders which blocks → CORE COMMUNICATIONS, INC.- MD 2593 FRIENDSVL MD
2004-03-18 301-799 0–9 XXXall 10 · 3 holders which blocks → CORE COMMUNICATIONS, INC.- MD 2593 KEEDYSVL MD
2004-03-18 301-882 0–9 XXXall 10 · 4 holders which blocks → CORE COMMUNICATIONS, INC.- MD 2593 NEW MARKET MD
2003-10-16 301-525 0–9 XXXall 10 · 2 holders which blocks → QUANTUM TELECOMMUNICATIONS, INC. - MD 2596 GAITHERSBG MD

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.