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 513
CINCINNATI BELL 251
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OH 125
T-MOBILE USA, INC. 79
NEW CINGULAR WIRELESS PCS, LLC - IL 55
LEVEL 3 COMMUNICATIONS, LLC - OH 39
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
— 513-542 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-543 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OH 6025 CINCINNATI OH
— 513-544 0XXX1XXX2XXX which blocks → T-MOBILE USA, INC. 6529 CINCINNATI OH
— 513-545 0XXX1XXX2XXX which blocks → T-MOBILE USA, INC. 6529 CINCINNATI OH
— 513-546 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX which blocks → T-MOBILE USA, INC. 6529 CINCINNATI OH
— 513-550 4XXX5XXX6XXX7XXX8XXX9XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CINCINNATI OH
— 513-551 0XXX3XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-552 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-553 not yet reported which blocks → CINCINNATI BELL 9348 CLERMONT OH
— 513-554 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-555 not yet reported which blocks → MULTIPLE OCN LISTING MULT DIR ASST OH
— 513-556 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-557 0XXX1XXX6XXX8XXX9XXX · 3 holders which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-558 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-559 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-560 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CINCINNATI OH
— 513-561 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-562 0XXX which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-563 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-564 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-565 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-566 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-569 2XXX3XXX · 2 holders which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-571 0XXX which blocks → T-MOBILE USA, INC. 6529 MIDDLETOWN OH
— 513-573 not yet reported which blocks → BRIGHTSPEED OF NORTHWEST OHIO, INC. 0661 MASON OH
— 513-574 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-575 6XXX8XXX which blocks → CINCINNATI BELL 9348 LTL MIAMI OH
— 513-576 not yet reported which blocks → CINCINNATI BELL 9348 LTL MIAMI OH
— 513-577 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-579 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-582 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OH 6025 CINCINNATI OH
— 513-583 not yet reported which blocks → CINCINNATI BELL 9348 LTL MIAMI OH
— 513-584 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-585 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-587 9XXX which blocks → LEVEL 3 COMMUNICATIONS, LLC - OH 4863 CINCINNATI OH
— 513-588 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-589 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-590 not yet reported which blocks → SPOK, INC. 6630 CINCINNATI OH
— 513-591 8XXX9XXX which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-593 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 OXFORD OH
— 513-594 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OH 6025 MIDDLETOWN OH
— 513-595 not yet reported which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-598 0XXX which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-599 0–9 XXXall 10 · 4 holders which blocks → EXIANT COMMUNICATIONS LLC 114J CINCINNATI OH
— 513-602 not yet reported which blocks → T-MOBILE USA, INC. 6529 CINCINNATI OH
— 513-603 0XXX9XXX · 2 holders which blocks → CINCINNATI BELL 9348 HAMILTON OH
— 513-604 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OH 6025 CINCINNATI OH
— 513-605 0XXX9XXX which blocks → CINCINNATI BELL 9348 CINCINNATI OH
— 513-607 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OH 6025 CINCINNATI OH
— 513-608 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OH 6025 CINCINNATI OH

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.