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 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
Clear Download CSV ↓
Recent NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
— 510-530 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-531 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-532 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-533 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-534 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-535 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-536 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-537 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-538 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-539 not yet reported which blocks → UTILITY TELECOM GROUP, LLC - CA 9262 OKLD MN-PD CA
— 510-540 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-541 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-542 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD BKLY CA
— 510-543 0XXX1XXX2XXX · 2 holders which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
— 510-544 1XXX9XXX · 2 holders which blocks → ONVOY, LLC - CA 649C OKLD TRNID CA
— 510-545 2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD ALMD CA
— 510-547 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-548 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-549 6XXX7XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-550 0XXX5XXX6XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD MN-PD CA
— 510-551 9XXX which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
— 510-553 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-554 not yet reported which blocks → 33 WIRELESS INC. 6967 HAYWARD CA
— 510-555 not yet reported which blocks → MULTIPLE OCN LISTING MULT DIR ASST CA
— 510-558 5XXX which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-559 0XXX which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-562 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-563 0XXX7XXX9XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-564 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD TRNID CA
— 510-565 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 FRNK MAIN CA
— 510-566 0–9 XXXall 10 · 2 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 HAYWARD CA
— 510-567 3XXX4XXX7XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-568 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-569 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-572 not yet reported which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 FRNK OLIVR CA
— 510-573 5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → COMCAST PHONE OF CALIFORNIA, LLC 394L FRNK OLIVR CA
— 510-574 5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-575 0–9 XXXall 10 · 2 holders which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
— 510-576 3XXX4XXX5XXX8XXX9XXX · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 HAYWARD CA
— 510-577 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-578 4XXX6XXX7XXX8XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK MAIN CA
— 510-579 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 FRNK MAIN CA
— 510-580 not yet reported which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK OLIVR CA
— 510-581 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-582 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-583 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-584 1XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 HAYWARD CA
— 510-585 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J FRNK MAIN CA
— 510-586 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → COMCAST PHONE OF CALIFORNIA, LLC 394L HAYWARD CA
— 510-587 9XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA

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.