NumberResearchThousands-blocks in 443-663
This prefix’s ten 1,000-number blocks and who holds each — 10 on record · from the daily NANPA thousands-block report, 09/20/2026
The ten 1,000-number thousand-blocks inside prefix 443-663 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 443 blocks
Most active assignees, all time — NPA 443
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
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2015-05-27 | 443-663-0XXX | 0000–0999 | Assigned | BALTIMORE-WASHINGTON TELEPHONE (BWT) | 8697 | WOODLAWN | MD |
| 2024-08-13 | 443-663-1XXX | 1000–1999 | Assigned | TERRA NOVA TELECOM INC. | 145J | WOODLAWN | MD |
| 2019-04-15 | 443-663-2XXX | 2000–2999 | Assigned | CORE COMMUNICATIONS, INC.- MD | 2593 | WOODLAWN | MD |
| 2016-02-15 | 443-663-3XXX | 3000–3999 | Assigned | ONVOY, LLC - MD | 876D | WOODLAWN | MD |
| 2015-09-22 | 443-663-4XXX | 4000–4999 | Assigned | ONVOY, LLC - MD | 876D | WOODLAWN | MD |
| 2016-02-15 | 443-663-5XXX | 5000–5999 | Assigned | ONVOY, LLC - MD | 876D | WOODLAWN | MD |
| — | 443-663-6XXX | 6000–6999 | Reserved | VERIZON MARYLAND, INC. | 9212 | WOODLAWN | MD |
| 2014-05-23 | 443-663-7XXX | 7000–7999 | Assigned | CENTURYLINK COMMUNICATIONS, LLC | 508J | WOODLAWN | MD |
| — | 443-663-8XXX | 8000–8999 | Reserved | VERIZON MARYLAND, INC. | 9212 | WOODLAWN | MD |
| 2016-05-03 | 443-663-9XXX | 9000–9999 | Assigned | IP HORIZON LLC | 515J | WOODLAWN | MD |
Source: NANPA Thousands Block Assignment Report (All Regions, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.