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
— 510-787 5XXX8XXX · 2 holders which blocks → PACIFIC BELL 9740 CROCKETT CA
— 510-788 0–9 XXXall 10 · 6 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD MN-PD CA
— 510-789 3XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 7240 FRNK MAIN CA
— 510-790 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-791 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-792 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-793 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-794 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-795 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-796 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-797 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-798 none assigned yet which blocks → METROPCS, INC. 5562 OKLD TRNID CA
— 510-799 not yet reported which blocks → PACIFIC BELL 9740 HRCUL-RODE CA
— 510-800 0–9 XXXwhole prefix which blocks → ONVOY, LLC - CA 649C OKLD ALMD CA
— 510-801 not yet reported which blocks → SPOK, INC. 6630 OKLD MN-PD CA
— 510-802 not yet reported which blocks → SPOK, INC. 6630 OKLD MN-PD CA
— 510-803 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 HRCUL-RODE CA
— 510-804 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 ELSBR-PINL CA
— 510-805 not yet reported which blocks → SPOK, INC. 6630 OKLD MN-PD CA
— 510-808 3XXX4XXX5XXX6XXX7XXX9XXX · 4 holders which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-809 5XXX6XXX7XXX which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J OKLD BKLY CA
— 510-811 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX CA
— 510-812 none assigned yet which blocks → METROPCS, INC. 5562 OKLD BKLY CA
— 510-813 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-814 not yet reported which blocks → PACIFIC BELL 9740 OKLD ALMD CA
— 510-815 3XXX7XXX8XXX9XXX · 3 holders which blocks → T-MOBILE USA, INC. 6529 ELSBR-PINL CA
— 510-816 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-817 0XXX2XXX4XXX6XXX · 3 holders which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-818 not yet reported which blocks → PACIFIC BELL 9740 FRNK MAIN CA
— 510-821 6XXX7XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD MN-PD CA
— 510-823 0XXX1XXX2XXX · 3 holders which blocks → T-MOBILE USA, INC. 6529 OKLD MN-PD CA
— 510-824 3XXX4XXX5XXX7XXX8XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 FRNK OLIVR CA
— 510-827 0–9 XXXall 10 · 4 holders which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
— 510-830 3XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → IP HORIZON LLC 515J OKLD MN-PD CA
— 510-832 9XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-834 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-835 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-836 5XXX9XXX which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-837 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7145 RICHMOND CA
— 510-839 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-840 not yet reported which blocks → UTILITY TELECOM GROUP, LLC - CA 9262 OKLD MN-PD CA
— 510-841 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-842 3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD FRTVL CA
— 510-843 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-844 4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 OKLD MN-PD CA
— 510-845 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-846 6XXX7XXX8XXX9XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD ALMD CA
— 510-848 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-849 6XXX7XXX · 2 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-851 6XXX7XXX8XXX9XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 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.