NumberResearchRecent thousands-block assignments
0 blocks assigned in the last 30 days · from the daily NANPA thousands-block report, 09/19/2026
Most carrier growth happens here, not at the prefix level: under number pooling, carriers receive individual 1,000-number blocks (e.g. 626-470-0XXX) within already-assigned prefixes. Assignments are initial assignments — the current serving carrier of individual numbers may differ due to portability.
Most active assignees, all time — NPA 520
New assignments by month
Sep 2026
Aug 2026
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2008-08-01 | 520-878-5XXX | 5000–5999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2008-03-06 | 520-344-6XXX | 6000–6999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2008-03-05 | 520-351-7XXX | 7000–7999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2007-11-14 | 520-351-5XXX | 5000–5999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2007-07-26 | 520-342-1XXX | 1000–1999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2007-07-26 | 520-342-2XXX | 2000–2999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2007-07-26 | 520-342-3XXX | 3000–3999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2007-03-16 | 520-269-4XXX | 4000–4999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2007-01-30 | 520-425-8XXX | 8000–8999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-11-09 | 520-396-1XXX | 1000–1999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-11-01 | 520-396-2XXX | 2000–2999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-09-07 | 520-289-8XXX | 8000–8999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-05-24 | 520-770-6XXX | 6000–6999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-03-01 | 520-647-8XXX | 8000–8999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-01-31 | 520-351-3XXX | 3000–3999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-01-31 | 520-351-4XXX | 4000–4999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-01-31 | 520-351-6XXX | 6000–6999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-01-31 | 520-351-8XXX | 8000–8999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2006-01-05 | 520-647-5XXX | 5000–5999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2005-10-04 | 520-495-7XXX | 7000–7999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
| 2004-10-28 | 520-777-2XXX | 2000–2999 | Assigned | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 7552 | TUCSON | AZ |
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.