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
2008-01-14 510-363 0–9 XXXall 10 · 4 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 HAYWARD CA
2007-11-28 510-356 0–9 XXXall 10 · 5 holders which blocks → PACIFIC BELL 9740 OKLD BKLY CA
2007-08-17 510-695 0–9 XXXall 10 · 4 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 HAYWARD CA
2007-07-02 510-314 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 HAYWARD CA
2007-02-15 510-230 0–9 XXXall 10 · 6 holders which blocks → T-MOBILE USA, INC. 6529 RICHMOND CA
2007-02-08 510-221 0–9 XXXall 10 · 7 holders which blocks → METROPCS, INC. 5562 RICHMOND CA
2006-09-21 510-778 0–9 XXXall 10 · 5 holders which blocks → COMCAST PHONE OF CALIFORNIA, LLC 394L RICHMOND CA
2004-08-18 510-948 0–9 XXXall 10 · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 HRCUL-RODE CA
2002-09-19 510-213 4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → T-MOBILE USA, INC. 6529 OKLD FRTVL CA
2002-09-19 510-417 1XXX2XXX3XXX4XXX6XXX7XXX8XXX · 3 holders which blocks → T-MOBILE USA, INC. 6529 ELSBR-PINL CA
2002-09-19 510-672 5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 RICHMOND CA
2002-09-19 510-717 7XXX which blocks → T-MOBILE USA, INC. 6529 OKLD BKLY CA
2002-08-21 510-461 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 HAYWARD CA
2002-06-14 510-676 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 FRNK MAIN CA
2002-05-17 510-754 none assigned yet which blocks → METROPCS, INC. 5562 HAYWARD CA
2001-12-26 510-282 not yet reported which blocks → T-MOBILE USA, INC. 6529 OKLD MN-PD CA
2001-12-26 510-375 6XXX which blocks → T-MOBILE USA, INC. 6529 RICHMOND CA
2001-12-26 510-396 not yet reported which blocks → T-MOBILE USA, INC. 6529 FRNK MAIN CA
2001-11-28 510-364 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 FRNK MAIN CA
2001-11-28 510-432 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 HAYWARD CA
2001-10-18 510-224 2XXX3XXX4XXX5XXX9XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 HRCUL-RODE CA
2001-10-18 510-825 none assigned yet which blocks → METROPCS, INC. 5562 HAYWARD CA
2001-09-21 510-776 not yet reported which blocks → METROPCS, INC. 5562 RICHMOND CA
2001-09-21 510-938 not yet reported which blocks → METROPCS, INC. 5562 FRNK MAIN CA
2001-09-19 510-415 not yet reported which blocks → T-MOBILE USA, INC. 6529 HAYWARD CA
2001-09-19 510-691 0XXX2XXX4XXX5XXX6XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 HRCUL-RODE CA
2001-08-22 510-472 not yet reported which blocks → METROPCS, INC. 5562 OKLD MN-PD CA
2001-08-22 510-706 not yet reported which blocks → METROPCS, INC. 5562 HAYWARD CA
2001-06-25 510-552 7XXX8XXX9XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 FRNK MAIN CA
2001-05-17 510-557 2XXX3XXX4XXX5XXX8XXX9XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 FRNK MAIN CA
2001-05-17 510-952 0XXX1XXX2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 7 holders which blocks → METROPCS, INC. 5562 FRNK GRNLF CA
2001-04-23 510-746 6XXX8XXX · 2 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J OKLD TRNID CA
2001-04-20 510-455 2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 4 holders which blocks → T-MOBILE USA, INC. 6529 CROCKETT CA
2001-04-20 510-689 1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → METROPCS, INC. 5562 OKLD FRTVL CA
2001-04-20 510-904 1XXX2XXX4XXX5XXX7XXX8XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CA 8826 OKLD TRNID CA
2001-03-22 510-677 0–9 XXXall 10 · 2 holders which blocks → METROPCS, INC. 5562 HAYWARD CA
2001-03-22 510-828 8XXX9XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 HAYWARD CA
2001-03-22 510-847 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA 6006 OKLD BKLY CA
2001-03-22 510-932 none assigned yet which blocks → T-MOBILE USA, INC. 6529 RICHMOND CA
2001-03-01 510-933 not yet reported which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J FRNK OLIVR CA
2001-01-25 510-866 0XXX2XXX · 2 holders which blocks → METROPCS, INC. 5562 OKLD FRTVL CA
— 510-202 not yet reported which blocks → UTILITY TELECOM GROUP, LLC - CA 9262 OKLD MN-PD CA
— 510-204 not yet reported which blocks → PACIFIC BELL 9740 OKLD BKLY CA
— 510-205 none assigned yet which blocks → METROPCS, INC. 5562 OKLD ALMD CA
— 510-206 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-207 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 OKLD MN-PD CA
— 510-208 not yet reported which blocks → PACIFIC BELL 9740 OKLD MN-PD CA
— 510-209 none assigned yet which blocks → METROPCS, INC. 5562 HAYWARD CA
— 510-211 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX CA
— 510-212 not yet reported which blocks → SPOK, INC. 6630 FRNK OLIVR 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.