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 858
U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 24
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
2022-05-27 858-318 0XXX1XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J CHULAVISTA CA
2019-05-16 858-293 0–9 XXXall 10 · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J SNDG MRMS CA
— 858-200 4XXX5XXX6XXX7XXX · 3 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J LA JOLLA CA
— 858-216 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J RNCHOPNQTS CA
— 858-217 4XXX5XXX6XXX7XXX · 3 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J RNCHOBRNDO CA
— 858-218 0XXX4XXX5XXX6XXX · 2 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J POWAY CA
— 858-300 5XXX6XXX7XXX which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J SNDG LVTA CA
— 858-356 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J DEL MAR CA
— 858-376 0XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J RNCHOBRNDO CA
— 858-400 0XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J RNCHOSANFE CA
— 858-413 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J POWAY CA
— 858-432 1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 4 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J RNCHOBRNDO CA
— 858-436 4XXX5XXX6XXX7XXX · 2 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J DEL MAR CA
— 858-444 0XXX5XXX6XXX7XXX which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J SNDG MRMS CA
— 858-519 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J DEL MAR CA
— 858-564 1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J SNDG MRMS CA
— 858-707 1XXX2XXX4XXX5XXX6XXX7XXX9XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J SNDG LVTA CA
— 858-713 0XXX1XXX4XXX which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J LA JOLLA CA
— 858-751 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J SNDG LVTA CA
— 858-777 not yet reported which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J LA JOLLA CA
— 858-860 0XXX1XXX4XXX5XXX6XXX9XXX · 4 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J SNDG MRMS CA
— 858-866 4XXX6XXX8XXX9XXX · 3 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J LA JOLLA CA
— 858-869 0XXX1XXX2XXX3XXX4XXX5XXX7XXX9XXX · 5 holders which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J LA JOLLA CA
— 858-875 not yet reported which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J LA JOLLA 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.