NumberResearch Membership · Data 09/19/2026

Recent prefix assignments

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

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
— 510-618 9XXX which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-620 4XXX which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-622 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-623 4XXX which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-624 1XXX9XXX · 2 holders which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-625 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-627 9XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-628 6XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-632 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-633 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-635 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-636 5XXX6XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-637 7XXX8XXX9XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-638 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-639 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-642 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-643 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-644 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-645 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-647 6XXX7XXX8XXX9XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-649 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-651 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-652 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-653 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-654 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-655 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-656 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-657 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-658 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-659 none assigned yet which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-661 2XXX3XXX · 2 holders which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-663 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-664 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-665 9XXX which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-666 4XXX5XXX6XXX7XXX · 4 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-667 2XXX which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-668 9XXX which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-669 5XXX which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-670 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-675 7XXX8XXX · 2 holders which blocks → PACIFIC BELL 9740 FRNK GRNLF CA
— 510-678 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-683 1XXX5XXX · 2 holders which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-687 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-690 3XXX4XXX5XXX7XXX8XXX · 4 holders which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-704 3XXX which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-705 0XXX1XXX2XXX3XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-713 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-723 4XXX which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-724 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-727 5XXX 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.