NumberResearchRecent thousands-block assignments
0 blocks assigned in the last 30 days · from the daily NANPA thousands-block report, 09/20/2026
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 331
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 |
|---|---|---|---|---|---|---|---|
| 2021-06-03 | 331-268-0XXX | 0000–0999 | Assigned | IP HORIZON LLC | 515J | SUGARGROVE | IL |
| 2021-06-03 | 331-341-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | PLANO | IL |
| 2021-06-03 | 331-500-8XXX | 8000–8999 | Assigned | IP HORIZON LLC | 515J | GENEVA | IL |
| 2021-06-03 | 331-867-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | YORKVILLE | IL |
| 2021-06-02 | 331-400-9XXX | 9000–9999 | Assigned | IP HORIZON LLC | 515J | OSWEGO | IL |
| 2021-06-02 | 331-465-8XXX | 8000–8999 | Assigned | IP HORIZON LLC | 515J | W CHICAGO | IL |
| 2021-05-21 | 331-261-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | LEMONT | IL |
| 2021-05-21 | 331-266-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | ST CHARLES | IL |
| 2021-05-21 | 331-899-0XXX | 0000–0999 | Assigned | IP HORIZON LLC | 515J | LOMBARD | IL |
| 2021-05-21 | 331-900-2XXX | 2000–2999 | Assigned | IP HORIZON LLC | 515J | ELMHURST | IL |
| 2021-05-20 | 331-356-0XXX | 0000–0999 | Assigned | IP HORIZON LLC | 515J | BARTLETT | IL |
| 2021-05-19 | 331-269-0XXX | 0000–0999 | Assigned | IP HORIZON LLC | 515J | AURORA | IL |
| 2021-05-19 | 331-345-0XXX | 0000–0999 | Assigned | IP HORIZON LLC | 515J | NAPERVILLE | IL |
| 2021-05-19 | 331-399-0XXX | 0000–0999 | Assigned | IP HORIZON LLC | 515J | DOWNERSGRV | IL |
| 2016-07-11 | 331-204-8XXX | 8000–8999 | Assigned | IP HORIZON LLC | 515J | NAPERVILLE | IL |
| 2016-07-11 | 331-300-8XXX | 8000–8999 | Assigned | IP HORIZON LLC | 515J | AURORA | IL |
| 2016-07-11 | 331-307-6XXX | 6000–6999 | Assigned | IP HORIZON LLC | 515J | LOMBARD | IL |
| 2016-07-11 | 331-716-8XXX | 8000–8999 | Assigned | IP HORIZON LLC | 515J | WHEATON | IL |
| 2016-07-11 | 331-771-6XXX | 6000–6999 | Assigned | IP HORIZON LLC | 515J | ST CHARLES | IL |
| 2016-07-11 | 331-803-9XXX | 9000–9999 | Assigned | IP HORIZON LLC | 515J | LEMONT | IL |
| 2016-07-11 | 331-979-8XXX | 8000–8999 | Assigned | IP HORIZON LLC | 515J | ELMHURST | IL |
| 2013-08-07 | 331-318-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | LEMONT | IL |
| 2013-04-09 | 331-209-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | ELMHURST | IL |
| 2013-04-09 | 331-422-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | ST CHARLES | IL |
| 2013-04-09 | 331-777-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | DOWNERSGRV | IL |
| 2013-03-20 | 331-301-1XXX | 1000–1999 | Assigned | IP HORIZON LLC | 515J | AURORA | IL |
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.