NumberResearch Membership · Data 09/19/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/19/2026

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 203
SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 338
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CT 61
NEW CINGULAR WIRELESS PCS, LLC - DC 52
OMNIPOINT COMMUNICATIONS, INC. - CT 47
LEVEL 3 COMMUNICATIONS, LLC - CT 41
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
Clear Download CSV ↓
Recent NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
— 203-512 not yet reported which blocks → OMNIPOINT COMMUNICATIONS, INC. - CT 6624 DANBURY CT
— 203-513 0XXX1XXX2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → AT&T - LOCAL 7421 HUNTINGTON CT
— 203-514 0XXX1XXX2XXX4XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CT 7143 MERIDEN CT
— 203-515 none assigned yet which blocks → OMNIPOINT COMMUNICATIONS, INC. - CT 6624 NORWALK CT
— 203-516 0XXX1XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CT 4800 ANSONIDRBY CT
— 203-517 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CT 4800 STAMFORD CT
— 203-521 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CT 6388 BRIDGEPORT CT
— 203-522 4XXX5XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 BRIDGEPORT CT
— 203-523 0XXX5XXX9XXX · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CT 7143 NORWALK CT
— 203-524 1XXX6XXX7XXX8XXX9XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 STAMFORD CT
— 203-525 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 WATERBURY CT
— 203-526 none assigned yet which blocks → METROPCS, INC. 5562 BRIDGEPORT CT
— 203-527 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 WATERBURY CT
— 203-528 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CT 4800 WATERBURY CT
— 203-529 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → AT&T - LOCAL 7421 WILTON CT
— 203-530 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CT 6388 NEW HAVEN CT
— 203-531 not yet reported which blocks → VERIZON NEW YORK, INC. 9104 BYRAM CT
— 203-532 5XXX8XXX · 2 holders which blocks → VERIZON NEW YORK, INC. 9104 BYRAM CT
— 203-533 0–9 XXXall 10 · 7 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - CT 4800 GUILFORD CT
— 203-534 6XXX8XXX9XXX which blocks → SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 BRIDGEPORT CT
— 203-535 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → COMCAST IP PHONE, LLC 318J NEW HAVEN CT
— 203-536 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CT 6388 STAMFORD CT
— 203-537 none assigned yet which blocks → METROPCS, INC. 5562 MERIDEN CT
— 203-538 5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → PAETEC ITEL, LLC 829J HUNTINGTON CT
— 203-539 0XXX1XXX2XXX6XXX9XXX · 3 holders which blocks → SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 STAMFORD CT
— 203-541 0XXX1XXX4XXX5XXX · 4 holders which blocks → SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 STAMFORD CT
— 203-542 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → AT&T - LOCAL 7421 GREENWICH CT
— 203-543 not yet reported which blocks → OMNIPOINT COMMUNICATIONS, INC. - CT 6624 BRIDGEPORT CT
— 203-544 2XXX3XXX4XXX5XXX6XXX · 4 holders which blocks → SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 GEORGETOWN CT
— 203-545 none assigned yet which blocks → METROPCS, INC. 5562 BRIDGEPORT CT
— 203-546 0XXX7XXX8XXX9XXX · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CT 7143 DANBURY CT
— 203-547 not yet reported which blocks → ONVOY, LLC - CT 639C STAMFORD CT
— 203-549 4XXX5XXX7XXX8XXX9XXX · 2 holders which blocks → PAETEC ITEL, LLC 829J BRIDGEPORT CT
— 203-550 not yet reported which blocks → OMNIPOINT COMMUNICATIONS, INC. - CT 6624 STAMFORD CT
— 203-551 0XXX1XXX4XXX9XXX · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CT 7143 BRIDGEPORT CT
— 203-552 2XXX which blocks → VERIZON NEW YORK, INC. 9104 BYRAM CT
— 203-553 7XXX9XXX · 2 holders which blocks → SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 NEW HAVEN CT
— 203-554 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 STAMFORD CT
— 203-555 not yet reported which blocks → MULTIPLE OCN LISTING MULT DIR ASST CT
— 203-556 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 BRIDGEPORT CT
— 203-557 0XXX3XXX4XXX6XXX8XXX which blocks → CABLEVISION LIGHTPATH, INC. - CT 4950 WESTPORT CT
— 203-558 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 WATERBURY CT
— 203-559 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - CT 7143 DARIEN CT
— 203-560 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - DC 4036 WATERBURY CT
— 203-561 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CT 6388 STAMFORD CT
— 203-562 not yet reported which blocks → SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 NEW HAVEN CT
— 203-563 4XXX8XXX · 2 holders which blocks → SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 WILTON CT
— 203-564 0XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → AT&T - LOCAL 7421 STAMFORD CT
— 203-565 0XXX which blocks → METROPCS, INC. 5562 WATERBURY CT
— 203-567 4XXX which blocks → PAETEC ITEL, LLC 829J HUNTINGTON CT

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.