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 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
— 510-728 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-729 1XXX2XXX3XXX5XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-732 4XXX which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-733 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD 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
— 510-741 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-742 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-744 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
— 510-752 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-758 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL 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
— 510-765 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL 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
— 510-777 6XXX which blocks → PACIFIC BELL 9740 OKLD TRNID 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
— 510-787 5XXX8XXX · 2 holders which blocks → PACIFIC BELL 9740 CROCKETT CA
— 510-790 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-791 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-792 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-793 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-794 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-795 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-796 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-797 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-799 not yet reported which blocks → PACIFIC BELL 9740 HRCUL-RODE CA
— 510-808 3XXX4XXX5XXX6XXX7XXX9XXX · 4 holders which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-814 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-817 0XXX2XXX4XXX6XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-818 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-832 9XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-834 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-835 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-836 5XXX9XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-839 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-841 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-843 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-845 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY 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.