NumberResearch Membership · Data 09/22/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/22/2026

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
— 585-272 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-273 none assigned yet which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-274 none assigned yet which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-276 0–9 XXXwhole prefix which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-277 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-279 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-288 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-291 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-292 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-293 5XXX6XXX7XXX8XXX · 4 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 CHURCHVL NY
— 585-306 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-320 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-321 5XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 HENRIETTA NY
— 585-323 none assigned yet which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-324 0XXX2XXX3XXX5XXX6XXX7XXX9XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-325 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-327 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-328 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-333 0XXX2XXX4XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-334 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 HENRIETTA NY
— 585-335 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 DANSVILLE NY
— 585-336 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-338 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-339 8XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-342 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-346 7XXX8XXX · 2 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 LIVONIA NY
— 585-347 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX · 6 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 W WEBSTER NY
— 585-350 4XXX5XXX6XXX8XXX9XXX · 2 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-359 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 HENRIETTA NY
— 585-367 1XXX4XXX5XXX6XXX · 4 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 HEMLOCK NY
— 585-368 2XXX5XXX8XXX · 2 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-374 1XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 NAPLES NY
— 585-377 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 FAIRPORT NY
— 585-381 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 EROCHESTER NY
— 585-382 1XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 LEICESTER NY
— 585-383 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 EROCHESTER NY
— 585-384 1XXX2XXX3XXX4XXX6XXX7XXX8XXX · 6 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 COHOCTON NY
— 585-385 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 EROCHESTER NY
— 585-387 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 EROCHESTER NY
— 585-388 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 FAIRPORT NY
— 585-389 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 EROCHESTER NY
— 585-393 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 CANANDAGUA NY
— 585-394 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 CANANDAGUA NY
— 585-395 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 BROCKPORT NY
— 585-396 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 CANANDAGUA NY
— 585-398 1XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 VICTOR NY
— 585-399 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-420 6XXX7XXX8XXX which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 ROCHESTER NY
— 585-421 6XXX7XXX8XXX · 3 holders which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 FAIRPORT NY
— 585-422 not yet reported which blocks → FRONTIER TELEPHONE OF ROCHESTER, INC. 0121 WEBSTER NY

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/22/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.