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
— 510-723 4XXX which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-724 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-725 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 TELECOM OF CALIFORNIA, LP - CA 7718 OKLD BKLY CA
— 510-727 5XXX which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-728 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-729 1XXX2XXX3XXX5XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-731 4XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 HAYWARD CA
— 510-732 4XXX which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-733 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-734 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 RICHMOND CA
— 510-735 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-739 4XXX7XXX · 2 holders which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-740 2XXX8XXX9XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD MN-PD CA
— 510-741 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-742 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-743 none assigned yet which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK OLIVR CA
— 510-744 8XXX which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-745 4XXX which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-747 2XXX5XXX8XXX9XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-748 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-749 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-750 1XXX9XXX · 2 holders which blocks → METROPCS, INC. 5562 HAYWARD CA
— 510-751 2XXX6XXX7XXX · 2 holders which blocks → ONVOY, LLC - CA 649C HAYWARD CA
— 510-752 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-755 8XXX9XXX · 2 holders which blocks → METROPCS, INC. 5562 HAYWARD CA
— 510-757 1XXX9XXX which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
— 510-758 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-759 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-760 none assigned yet which blocks → METROPCS, INC. 5562 HAYWARD CA
— 510-761 0XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-762 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-763 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-764 0XXX3XXX5XXX7XXX8XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD ALMD CA
— 510-765 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-768 5XXX7XXX8XXX · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD MN-PD CA
— 510-769 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-770 4XXX6XXX7XXX · 2 holders which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-771 4XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 FRNK OLIVR CA
— 510-772 none assigned yet which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
— 510-773 none assigned yet which blocks → T-MOBILE USA, INC. 6529 OKLD MN-PD CA
— 510-774 none assigned yet which blocks → T-MOBILE USA, INC. 6529 OKLD MN-PD CA
— 510-777 6XXX which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-779 1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 ELSBR-PINL CA
— 510-780 2XXX3XXX6XXX · 3 holders which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-781 2XXX9XXX · 2 holders which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-782 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-783 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-784 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-785 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-786 7XXX8XXX which blocks → PACIFIC BELL 9740 HAYWARD 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.