NumberResearch Membership · Data 09/20/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/20/2026

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 510
PACIFIC BELL 278
NEW CINGULAR WIRELESS PCS, LLC 78
T-MOBILE USA, INC. 65
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 60
METROPCS, INC. 45
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
— 510-852 3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-853 5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-854 0XXX3XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → BANDWIDTH.COM CLEC, LLC - CA 981E ELSBR-PINL CA
— 510-855 0XXX1XXX2XXX3XXX4XXX5XXX6XXX which blocks → UTILITY TELECOM GROUP, LLC - CA 9262 OKLD MN-PD CA
— 510-856 2XXX5XXX6XXX7XXX8XXX · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 HAYWARD CA
— 510-857 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK MAIN CA
— 510-858 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX9XXX · 4 holders which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
— 510-859 3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J OKLD BKLY CA
— 510-860 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 RICHMOND CA
— 510-861 3XXX4XXX5XXX7XXX8XXX9XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 HAYWARD CA
— 510-862 2XXX3XXX4XXX5XXX7XXX8XXX9XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 HAYWARD CA
— 510-863 0XXX1XXX2XXX3XXX4XXX7XXX8XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD ALMD CA
— 510-864 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-865 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-867 2XXX3XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 OKLD MN-PD CA
— 510-868 7XXX which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD BKLY CA
— 510-869 7XXX9XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-870 4XXX6XXX7XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 FRNK GRNLF CA
— 510-872 2XXX which blocks → METROPCS, INC. 5562 OKLD ALMD CA
— 510-873 1XXX3XXX9XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-874 5XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-875 0XXX3XXX4XXX5XXX8XXX9XXX which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD TRNID CA
— 510-877 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 OKLD TRNID CA
— 510-878 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → COMCAST PHONE OF CALIFORNIA, LLC 394L OKLD TRNID CA
— 510-879 5XXX6XXX7XXX · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 OKLD MN-PD CA
— 510-880 1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → ONVOY, LLC - CA 649C HAYWARD CA
— 510-881 3XXX6XXX which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-882 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-883 3XXX4XXX8XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-884 not yet reported which blocks → UTILITY TELECOM GROUP, LLC - CA 9262 HAYWARD CA
— 510-885 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-886 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-887 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-888 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-889 none assigned yet which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-891 1XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-892 1XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → ONVOY, LLC - CA 649C HAYWARD CA
— 510-893 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-894 5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → COMCAST PHONE OF CALIFORNIA, LLC 394L FRNK MAIN CA
— 510-895 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-896 0XXX3XXX5XXX7XXX9XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 FRNK MAIN CA
— 510-897 0XXX3XXX5XXX6XXX7XXX9XXX · 5 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 FRNK OLIVR CA
— 510-898 6XXX8XXX · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 OKLD BKLY CA
— 510-899 0–9 XXXall 10 · 4 holders which blocks → BANDWIDTH.COM CLEC, LLC - CA 981E OKLD MN-PD CA
— 510-900 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLC - CA 649C OKLD BKLY CA
— 510-903 4XXX6XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD MN-PD CA
— 510-907 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-908 6XXX7XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-909 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 HAYWARD CA
— 510-910 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.