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
— 510-214 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 OKLD ALMD CA
— 510-215 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-217 8XXX which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 OKLD ALMD CA
— 510-218 not yet reported which blocks → SPOK, INC. 6630 FRNK OLIVR CA
— 510-219 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-220 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-222 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-223 not yet reported which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-225 5XXX8XXX which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD BKLY CA
— 510-226 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-227 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 TELECOM OF CALIFORNIA, LP - CA 7718 OKLD ALMD CA
— 510-228 2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD FRTVL CA
— 510-229 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-231 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-232 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-233 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-234 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-235 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-236 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-237 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-238 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-239 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J OKLD ALMD CA
— 510-240 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 8 holders which blocks → LEVEL 3 TELECOM OF CALIFORNIA, LP - CA 7718 FRNK GRNLF CA
— 510-242 not yet reported which blocks → PACIFIC BELL 9740 RICHMOND CA
— 510-243 4XXX5XXX · 2 holders which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-245 not yet reported which blocks → PACIFIC BELL 9740 HRCUL-RODE CA
— 510-247 none assigned yet which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-248 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 FRNK MAIN CA
— 510-249 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-250 2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD MN-PD CA
— 510-251 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-252 not yet reported which blocks → PACIFIC BELL 9740 FRNK OLIVR CA
— 510-253 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 TELECOM OF CALIFORNIA, LP - CA 7718 RICHMOND CA
— 510-256 0–9 XXXall 10 · 7 holders which blocks → BANDWIDTH.COM CLEC, LLC - CA 981E CROCKETT CA
— 510-257 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 FRNK OLIVR CA
— 510-258 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-259 8XXX9XXX · 2 holders which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-260 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → COMCAST PHONE OF CALIFORNIA, LLC 394L RICHMOND CA
— 510-261 not yet reported which blocks → PACIFIC BELL 9740 OKLD FRTVL CA
— 510-262 3XXX6XXX · 2 holders which blocks → PACIFIC BELL 9740 ELSBR-PINL CA
— 510-263 3XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-264 2XXX7XXX · 2 holders which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-265 4XXX9XXX which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-266 2XXX4XXX8XXX9XXX · 4 holders which blocks → PACIFIC BELL 9740 HAYWARD CA
— 510-267 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-268 6XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-269 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 7 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 OKLD FRTVL CA
— 510-270 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK OLIVR CA
— 510-271 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-272 7XXX8XXX 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.