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
Clear Download CSV ↓
Recent NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
— 510-273 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-274 0–9 XXXall 10 · 8 holders which blocks → UTILITY TELECOM GROUP, LLC - CA 9262 HAYWARD CA
— 510-275 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → ONVOY, LLC - CA 649C ELSBR-PINL CA
— 510-276 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-277 2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD BKLY CA
— 510-278 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-279 3XXX4XXX6XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 FRNK OLIVR CA
— 510-280 0XXX3XXX4XXX5XXX7XXX8XXX9XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD BKLY CA
— 510-281 not yet reported which blocks → ONVOY, LLC - CA 649C OKLD MN-PD CA
— 510-283 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ELSBR-PINL CA
— 510-284 2XXX3XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-285 6XXX7XXX8XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 OKLD MN-PD CA
— 510-286 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-287 6XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-288 not yet reported which blocks → ONVOY, LLC - CA 649C OKLD MN-PD CA
— 510-289 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-290 none assigned yet which blocks → T-MOBILE USA, INC. 6529 OKLD MN-PD CA
— 510-291 4XXX which blocks → ONVOY, LLC - CA 649C OKLD MN-PD CA
— 510-292 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-293 6XXX which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-295 3XXX4XXX5XXX7XXX8XXX9XXX · 2 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD BKLY CA
— 510-296 0–9 XXXall 10 · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 HRCUL-RODE CA
— 510-297 not yet reported which blocks → PACIFIC BELL 9740 OKLD TRNID CA
— 510-299 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 FRNK MAIN CA
— 510-300 4XXX5XXX7XXX · 2 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J HAYWARD CA
— 510-301 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-302 5XXX7XXX8XXX9XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-303 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 HAYWARD CA
— 510-304 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 FRNK MAIN CA
— 510-305 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 HAYWARD CA
— 510-306 1XXX2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 4 holders which blocks → METROPCS, INC. 5562 OKLD ALMD CA
— 510-307 5XXX6XXX · 2 holders which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-308 not yet reported which blocks → SPOK, INC. 6630 OKLD MN-PD CA
— 510-311 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX CA
— 510-313 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 HRCUL-RODE CA
— 510-315 not yet reported which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 HAYWARD CA
— 510-316 none assigned yet which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-317 not yet reported which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-318 3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-321 not yet reported which blocks → SPOK, INC. 6630 OKLD MN-PD CA
— 510-322 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 HRCUL-RODE CA
— 510-323 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 RICHMOND CA
— 510-324 5XXX6XXX7XXX9XXX · 4 holders which blocks → PACIFIC BELL 9740 FRNK GRNLF CA
— 510-325 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-326 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-327 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → ONVOY, LLC - CA 649C HRCUL-RODE CA
— 510-329 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 HAYWARD CA
— 510-331 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 HAYWARD CA
— 510-332 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-333 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD 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.