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 503
T-MOBILE USA, INC. 56
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
2006-01-12 503-927 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
2005-10-21 503-841 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
2005-01-26 503-442 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
2004-09-17 503-664 0–9 XXXall 10 · 7 holders which blocks → T-MOBILE USA, INC. 6529 BEAVER OR
2001-12-03 503-470 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → T-MOBILE USA, INC. 6529 SEASIDE OR
— 503-209 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-267 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-269 1XXX2XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 SALEM OR
— 503-309 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-317 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-334 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-358 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-380 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-381 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-409 not yet reported which blocks → T-MOBILE USA, INC. 6529 SALEM OR
— 503-420 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → T-MOBILE USA, INC. 6529 DALLAS OR
— 503-421 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-422 4XXX which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-449 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-481 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-490 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-515 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-516 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-519 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-544 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-560 8XXX9XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 MCMINNVL OR
— 503-569 2XXX8XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 SALEM OR
— 503-572 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-602 0XXX2XXX3XXX4XXX5XXX6XXX7XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 SALEM OR
— 503-740 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-741 1XXX2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → T-MOBILE USA, INC. 6529 ASTORIA OR
— 503-750 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-752 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-753 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-754 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-756 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-757 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-793 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-809 0XXX2XXX4XXX5XXX7XXX8XXX · 3 holders which blocks → T-MOBILE USA, INC. 6529 NORTH PL OR
— 503-810 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-849 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-851 not yet reported which blocks → T-MOBILE USA, INC. 6529 SALEM OR
— 503-884 6XXX which blocks → T-MOBILE USA, INC. 6529 SALEM OR
— 503-888 not yet reported which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-890 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-891 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-901 2XXX3XXX4XXX7XXX8XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-914 3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → T-MOBILE USA, INC. 6529 PORTLAND OR
— 503-917 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → T-MOBILE USA, INC. 6529 DALLAS OR
— 503-932 none assigned yet which blocks → T-MOBILE USA, INC. 6529 SALEM OR

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.