NumberResearch Membership · Data 09/19/2026

Thousands-blocks in 301-433

This prefix’s ten 1,000-number blocks and who holds each — 10 on record · from the daily NANPA thousands-block report, 09/19/2026

Full prefixes (NXX) Thousands-blocks (1,000-number pools)

The ten 1,000-number thousand-blocks inside prefix 301-433 and who was initially assigned each. Under pooling these blocks often belong to different carriers — the single prefix-level “assignee” is usually just the pool / code holder, not who holds the numbers. ← all 301 blocks

Most active assignees, all time — NPA 301
OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 4
YMAX COMMUNICATIONS CORP. - MD 1
VERIZON MARYLAND, INC. 1
ONVOY, LLC - MD 1
METROPCS, INC. 1
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 thousands-block assignments
AssignedThousands-blockLast 4 digitsStatusAssigneeOCNRate centerState
— 301-433-0XXX 0000–0999Reserved VERIZON MARYLAND, INC. 9212 WSHNGTNZN5 MD
2007-12-13 301-433-1XXX 1000–1999Assigned OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 6855 WSHNGTNZN5 MD
2008-05-19 301-433-2XXX 2000–2999Assigned OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 6855 WSHNGTNZN5 MD
2008-05-19 301-433-3XXX 3000–3999Assigned OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 6855 WSHNGTNZN5 MD
2008-09-24 301-433-4XXX 4000–4999Assigned YMAX COMMUNICATIONS CORP. - MD 281E WSHNGTNZN5 MD
2008-03-14 301-433-5XXX 5000–5999Assigned OMNIPOINT COMMUNICATIONS CAP OPERATIONS, LLC 6855 WSHNGTNZN5 MD
2019-04-11 301-433-6XXX 6000–6999Assigned CORE COMMUNICATIONS, INC.- MD 2593 WSHNGTNZN5 MD
2015-05-28 301-433-7XXX 7000–7999Assigned ONVOY, LLC - MD 876D WSHNGTNZN5 MD
2015-07-30 301-433-8XXX 8000–8999Assigned COMCAST IP PHONE, LLC 318J WSHNGTNZN5 MD
2019-11-05 301-433-9XXX 9000–9999Assigned METROPCS, INC. 5562 WSHNGTNZN5 MD

Source: NANPA Thousands Block Assignment Report (All Regions, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.