NumberResearchThousands-blocks in 520-305
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
The ten 1,000-number thousand-blocks inside prefix 520-305 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 520 blocks
Most active assignees, all time — NPA 520
New assignments by month
Sep 2026
Aug 2026
Jul 2026
Jun 2026
May 2026
Apr 2026
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Feb 2026
Jan 2026
Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2007-10-15 | 520-305-0XXX | 0000–0999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ | 6572 | TUCSON | AZ |
| 2008-01-29 | 520-305-1XXX | 1000–1999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ | 6572 | TUCSON | AZ |
| 2008-01-29 | 520-305-2XXX | 2000–2999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ | 6572 | TUCSON | AZ |
| 2008-02-13 | 520-305-3XXX | 3000–3999 | Assigned | COMCAST IP PHONE, LLC | 318J | TUCSON | AZ |
| 2008-02-13 | 520-305-4XXX | 4000–4999 | Assigned | COMCAST IP PHONE, LLC | 318J | TUCSON | AZ |
| 2008-01-07 | 520-305-5XXX | 5000–5999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ | 6572 | TUCSON | AZ |
| 2008-01-07 | 520-305-6XXX | 6000–6999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ | 6572 | TUCSON | AZ |
| 2008-03-12 | 520-305-7XXX | 7000–7999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC | 6010 | TUCSON | AZ |
| 2008-03-12 | 520-305-8XXX | 8000–8999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC | 6010 | TUCSON | AZ |
| 2008-05-06 | 520-305-9XXX | 9000–9999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - AZ | 3285 | 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.