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 623
QWEST CORPORATION 97
T-MOBILE USA, INC. 39
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 31
ONVOY, LLC - AZ 29
NEW CINGULAR WIRELESS PCS, LLC 22
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
— 623-376 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-383 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLC - AZ 630E PHOENIX AZ
— 623-385 2XXX5XXX6XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 TELECOM OF ARIZONA, LLC - AZ 7552 PHOENIX AZ
— 623-386 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-388 1XXX3XXX4XXX6XXX7XXX · 3 holders which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-393 none assigned yet which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-398 4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → XO ARIZONA, INC. 4793 PHOENIX AZ
— 623-399 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-411 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX AZ
— 623-412 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-434 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-435 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-444 0XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - AZ 7217 PHOENIX AZ
— 623-445 1XXX which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-451 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-463 none assigned yet which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-465 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-466 0–9 XXXall 10 · 3 holders which blocks → COMCAST IP PHONE, LLC 318J PHOENIX AZ
— 623-474 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-476 2XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 PHOENIX AZ
— 623-478 2XXX which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-486 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-487 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-492 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-505 3XXX7XXX8XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - AZ 3285 PHOENIX AZ
— 623-511 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX AZ
— 623-512 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX which blocks → ELECTRIC LIGHTWAVE LLC DBA ALLSTREAM 7175 PHOENIX AZ
— 623-516 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-518 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 PHOENIX AZ
— 623-521 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-523 1XXX2XXX3XXX4XXX7XXX9XXX which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-533 3XXX4XXX5XXX6XXX which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-535 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-536 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-537 5XXX7XXX · 2 holders which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-544 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-546 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-547 5XXX6XXX7XXX9XXX · 2 holders which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-551 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-555 not yet reported which blocks → MULTIPLE OCN LISTING MULT DIR ASST AZ
— 623-556 3XXX6XXX7XXX which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-561 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-562 0–9 XXXall 10 · 3 holders which blocks → COMCAST IP PHONE, LLC 318J PHOENIX AZ
— 623-566 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-570 not yet reported which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-572 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-580 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-581 4XXX which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-582 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ
— 623-583 not yet reported which blocks → QWEST CORPORATION 9636 PHOENIX AZ

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.