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
— 510-334 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 RICHMOND CA
— 510-335 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLC - CA 649C FRNK MAIN CA
— 510-336 4XXX5XXX6XXX8XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-337 4XXX which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-338 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 7 holders which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-339 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-341 not yet reported which blocks → CA
— 510-342 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 6 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J HAYWARD CA
— 510-343 1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J OKLD TRNID CA
— 510-344 1XXX2XXX3XXX4XXX5XXX6XXX7XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 FRNK OLIVR CA
— 510-346 5XXX6XXX9XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-347 7XXX8XXX9XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-348 not yet reported which blocks → 33 WIRELESS INC. 6967 OKLD MN-PD CA
— 510-349 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 RICHMOND CA
— 510-350 1XXX3XXX5XXX6XXX7XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 OKLD MN-PD CA
— 510-351 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-352 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-353 3XXX which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-354 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-355 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD ALMD CA
— 510-357 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-360 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-366 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 FRNK MAIN CA
— 510-367 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 RICHMOND CA
— 510-368 7XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-372 3XXX4XXX5XXX6XXX7XXX9XXX · 2 holders which blocks → ONVOY, LLC - CA 649C HAYWARD CA
— 510-373 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → ONVOY, LLC - CA 649C OKLD ALMD CA
— 510-374 0XXX2XXX4XXX5XXX6XXX8XXX9XXX · 5 holders which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-376 none assigned yet which blocks → METROPCS, INC. 5562 FRNK MAIN CA
— 510-377 none assigned yet which blocks → T-MOBILE USA, INC. 6529 FRNK MAIN CA
— 510-378 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 FRNK MAIN CA
— 510-379 0XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 TELECOM OF CALIFORNIA, LP - CA 7718 OKLD MN-PD CA
— 510-380 0XXX2XXX3XXX4XXX8XXX9XXX · 4 holders which blocks → ONVOY, LLC - CA 649C OKLD MN-PD CA
— 510-381 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-382 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-383 0XXX6XXX7XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-384 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-385 none assigned yet which blocks → T-MOBILE USA, INC. 6529 OKLD MN-PD CA
— 510-386 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 FRNK MAIN CA
— 510-387 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-388 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-390 7XXX8XXX9XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-393 none assigned yet which blocks → T-MOBILE USA, INC. 6529 OKLD MN-PD CA
— 510-394 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 OKLD TRNID CA
— 510-395 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 OKLD FRTVL CA
— 510-400 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK GRNLF CA
— 510-401 0XXX1XXX3XXX4XXX5XXX7XXX9XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J FRNK GRNLF CA
— 510-402 0–9 XXXall 10 · 5 holders which blocks → BANDWIDTH.COM CLEC, LLC - CA 981E FRNK MAIN CA
— 510-403 0XXX1XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J FRNK OLIVR CA
— 510-404 2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 FRNK GRNLF 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.