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
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Recent NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
— 510-473 2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD ALMD CA
— 510-474 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK GRNLF CA
— 510-475 not yet reported which blocks → PACIFIC BELL 9740 FRNK GRNLF CA
— 510-476 9XXX which blocks → PACIFIC BELL 9740 FRNK GRNLF CA
— 510-477 not yet reported which blocks → PACIFIC BELL 9740 FRNK GRNLF CA
— 510-478 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 RICHMOND CA
— 510-479 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 7 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 OKLD FRTVL CA
— 510-481 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-482 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-483 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-484 1XXX9XXX which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
— 510-485 0–9 XXXall 10 · 3 holders which blocks → METROPCS, INC. 5562 OKLD FRTVL CA
— 510-486 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-487 not yet reported which blocks → PACIFIC BELL 9740 FRNK GRNLF CA
— 510-488 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD FRTVL CA
— 510-489 not yet reported which blocks → PACIFIC BELL 9740 FRNK GRNLF CA
— 510-490 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-491 0XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 FRNK GRNLF CA
— 510-492 3XXX6XXX · 2 holders which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-493 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK MAIN CA
— 510-494 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-495 0XXX1XXX4XXX5XXX6XXX7XXX9XXX · 4 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-496 1XXX3XXX4XXX9XXX · 3 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J OKLD MN-PD CA
— 510-497 0XXX1XXX4XXX which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK OLIVR CA
— 510-498 5XXX6XXX which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-499 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-500 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD FRTVL CA
— 510-501 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-502 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-503 not yet reported which blocks → UTILITY TELECOM GROUP, LLC - CA 9262 OKLD MN-PD CA
— 510-504 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-505 4XXX8XXX · 2 holders which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-506 7XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-507 7XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-508 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-511 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX CA
— 510-512 0XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 4 holders which blocks → T-MOBILE USA, INC. 6529 HAYWARD CA
— 510-515 not yet reported which blocks → SPOK, INC. 6630 OKLD MN-PD CA
— 510-517 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-518 0–9 XXXall 10 · 7 holders which blocks → PEERLESS NETWORK OF CALIFORNIA, LLC - CA 373F FRNK MAIN CA
— 510-520 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-521 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-522 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-523 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-524 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-525 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-526 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-527 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-528 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-529 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → PACIFIC BELL 9740 OKLD BKLY 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.