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 815
ILLINOIS BELL TEL CO 157
FRONTIER NORTH, INC. - IL 133
LEVEL 3 COMMUNICATIONS, LLC - IL 76
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 50
AERO NORTH COMMUNICATIONS, INC. - IL 43
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
— 815-572 1XXX2XXX4XXX6XXX7XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - IL 6115 MARENGO IL
— 815-574 not yet reported which blocks → AERO NORTH COMMUNICATIONS, INC. - IL 443F HARMON IL
— 815-575 5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 WOODSTOCK IL
— 815-576 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX · 5 holders which blocks → AERO NORTH COMMUNICATIONS, INC. - IL 443F POLO IL
— 815-577 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 PLAINFIELD IL
— 815-578 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 MCHENRY IL
— 815-579 3XXX4XXX5XXX6XXX7XXX · 3 holders which blocks → METROPCS, INC. 5562 LA SALLE IL
— 815-583 not yet reported which blocks → AERO NORTH COMMUNICATIONS, INC. - IL 443F MORRISON IL
— 815-584 0XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → ILLINOIS BELL TEL CO 9329 DWIGHT IL
— 815-586 not yet reported which blocks → C-R TELEPHONE CO. 1009 RANSOM IL
— 815-588 5XXX9XXX · 2 holders which blocks → ILLINOIS BELL TEL CO 9329 LOCKPORT IL
— 815-589 not yet reported which blocks → CITIZENS TELECOM CO ILLINOIS-FRONTIER CITIZENS -IL 1183 FULTON IL
— 815-591 0XXX1XXX4XXX5XXX6XXX · 4 holders which blocks → FRONTIER NORTH, INC. - IL 1036 HANOVER IL
— 815-592 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 KANKAKEE IL
— 815-593 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 DE KALB IL
— 815-594 0XXX1XXX4XXX5XXX7XXX · 4 holders which blocks → FRONTIER NORTH, INC. - IL 1036 APPLERIVER IL
— 815-597 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → FRONTIER NORTH, INC. - IL 1015 GARDENPRRI IL
— 815-598 0XXX4XXX5XXX8XXX · 3 holders which blocks → FRONTIER NORTH, INC. - IL 1036 MASSBACH IL
— 815-599 1XXX2XXX9XXX · 2 holders which blocks → FRONTIER NORTH, INC. - IL 1036 FREEPORT IL
— 815-601 0–9 XXXall 10 · 2 holders which blocks → UNITED STATES CELLULAR - IL 6265 ROCKFORD IL
— 815-602 not yet reported which blocks → FIRST COMMUNICATIONS, LLC 460K KANKAKEE IL
— 815-606 not yet reported which blocks → FIRST COMMUNICATIONS, LLC 460K OTTAWA IL
— 815-611 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX IL
— 815-614 0–9 XXXall 10 · 4 holders which blocks → ILLINOIS BELL TEL CO 9329 KANKAKEE IL
— 815-617 0XXX1XXX2XXX3XXX5XXX7XXX8XXX9XXX · 7 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 OTTAWA IL
— 815-621 none assigned yet which blocks → T-MOBILE USA, INC. 6529 ROCKFORD IL
— 815-622 none assigned yet which blocks → ILLINOIS BELL TEL CO 9329 STERLING IL
— 815-623 0XXX4XXX · 2 holders which blocks → FRONTIER NORTH, INC. - IL 1015 ROSCOE IL
— 815-624 3XXX9XXX · 2 holders which blocks → FRONTIER NORTH, INC. - IL 1015 ROCKTON IL
— 815-625 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 STERLING IL
— 815-626 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 STERLING IL
— 815-627 0XXX1XXX4XXX5XXX6XXX · 4 holders which blocks → FRONTIER NORTH, INC. - IL 1015 PAW PAW IL
— 815-628 2XXX4XXX5XXX6XXX8XXX9XXX · 6 holders which blocks → FRONTIER NORTH, INC. - IL 1015 W BROOKLYN IL
— 815-629 0XXX3XXX4XXX6XXX · 2 holders which blocks → FRONTIER NORTH, INC. - IL 1015 SHIRLAND IL
— 815-631 9XXX which blocks → ILLINOIS BELL TEL CO 9329 STERLING IL
— 815-632 3XXX which blocks → ILLINOIS BELL TEL CO 9329 STERLING IL
— 815-633 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 ROCKFORD IL
— 815-634 1XXX6XXX7XXX · 2 holders which blocks → ILLINOIS BELL TEL CO 9329 COAL CITY IL
— 815-635 0XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → FRONTIER NORTH, INC. - IL 1015 CHATSWORTH IL
— 815-636 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 ROCKFORD IL
— 815-637 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 ROCKFORD IL
— 815-638 7XXX8XXX9XXX · 3 holders which blocks → FRONTIER NORTH, INC. - IL 1015 LA MOILLE IL
— 815-639 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 ROCKFORD IL
— 815-642 2XXX3XXX5XXX6XXX7XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - IL 6115 MINOOKA IL
— 815-643 3XXX4XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → FRONTIER NORTH, INC. - IL 1015 DOVER IL
— 815-644 0XXX1XXX2XXX4XXX5XXX6XXX8XXX which blocks → RCN TELECOM SERVICES OF ILLINIOS, INC. - IL 8702 CRESCENTCY IL
— 815-645 0XXX3XXX5XXX6XXX7XXX9XXX · 3 holders which blocks → FRONTIER NORTH, INC. - IL 1015 STILMANVLY IL
— 815-646 2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → FRONTIER NORTH, INC. - IL 1015 TISKILWA IL
— 815-647 0XXX1XXX2XXX4XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → MEDIACOM TELEPHONY OF ILLINOIS, LLC - IL 846F CULLOM IL
— 815-648 0XXX5XXX7XXX8XXX9XXX · 4 holders which blocks → FRONTIER NORTH, INC. - IL 1015 HEBRON IL

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.