NumberResearch Membership · Data 09/23/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/23/2026

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 585
FRONTIER TELEPHONE OF ROCHESTER, INC. 186
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
— 585-663 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-669 3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 SPRINGWTR NY
— 585-670 2XXX3XXX6XXX · 3 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 W WEBSTER NY
— 585-671 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 W WEBSTER NY
— 585-719 4XXX5XXX6XXX7XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-720 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-722 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-723 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-726 none assigned yet which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-728 1XXX4XXX6XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 WAYLAND NY
— 585-742 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 VICTOR NY
— 585-768 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 LE ROY NY
— 585-770 0XXX1XXX2XXX3XXX4XXX7XXX8XXX · 4 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-771 0XXX7XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-777 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-783 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-786 7XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 WARSAW NY
— 585-787 4XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 W WEBSTER NY
— 585-865 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-872 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 WEBSTER NY
— 585-889 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 SCOTTSVL NY
— 585-899 0XXX1XXX2XXX3XXX5XXX7XXX8XXX9XXX · 6 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 EROCHESTER NY
— 585-921 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-922 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-924 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 VICTOR NY
— 585-935 1XXX7XXX · 2 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-936 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-939 4XXX5XXX6XXX7XXX · 2 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-955 3XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-956 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 XXXXXXXXXX NY
— 585-964 1XXX4XXX6XXX · 3 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 HAMLIN NY
— 585-966 2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 2 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-971 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 XXXXXXXXXX NY
— 585-974 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-975 none assigned yet which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-987 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/23/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.