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 617
LEVEL 3 COMMUNICATIONS, LLC - MA 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
2004-09-02 617-820 0–9 XXXall 10 · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BOSTON MA
2004-08-04 617-938 0–9 XXXall 10 · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BOSTON MA
2002-02-27 617-765 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 SO BOSTON MA
2001-12-15 617-275 0XXX1XXX3XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BOSTON MA
— 617-213 0–9 XXXall 10 · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 NEWTON MA
— 617-231 2XXX3XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 WATERTOWN MA
— 617-245 0XXX which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 CAMBRIDGE MA
— 617-273 7XXX which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 MILTON MA
— 617-297 1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 DORCHESTER MA
— 617-314 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BOSTON MA
— 617-380 1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 CHARLESTN MA
— 617-395 3XXX which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 CAMBRIDGE MA
— 617-401 0–9 XXXall 10 · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 CAMBRIDGE MA
— 617-500 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 CAMBRIDGE MA
— 617-505 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BROOKLINE MA
— 617-517 none assigned yet which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BOSTON MA
— 617-583 0XXX2XXX3XXX7XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 CAMBRIDGE MA
— 617-606 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 ROXBURY MA
— 617-622 3XXX4XXX5XXX6XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 SO BOSTON MA
— 617-639 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 QUINCY MA
— 617-648 1XXX6XXX7XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BOSTON MA
— 617-676 0XXX1XXX2XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 JAMAICA PL MA
— 617-690 0–9 XXXall 10 · 7 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 MILTON MA
— 617-729 1XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 QUINCY MA
— 617-741 0XXX1XXX2XXX3XXX5XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 SOMERVILLE MA
— 617-751 0XXX1XXX2XXX3XXX5XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BROOKLINE MA
— 617-762 1XXX2XXX4XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 NEWTON MA
— 617-826 1XXX4XXX5XXX6XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BELMONT MA
— 617-837 0XXX1XXX2XXX3XXX4XXX5XXX6XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 QUINCY MA
— 617-841 2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 WINTHROP MA
— 617-848 6XXX7XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BOSTON MA
— 617-870 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BRIGHTON MA
— 617-895 4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 EASTBOSTON MA
— 617-906 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BROOKLINE MA
— 617-925 1XXX2XXX5XXX6XXX7XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 BRIGHTON MA
— 617-934 0–9 XXXall 10 · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 QUINCY MA
— 617-990 0–9 XXXall 10 · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 HYDE PARK MA
— 617-996 0XXX1XXX3XXX4XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 SOMERVILLE MA
— 617-997 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MA 4018 EASTBOSTON MA

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.