NumberResearchRecent thousands-block assignments
0 blocks assigned in the last 30 days · from the daily NANPA thousands-block report, 09/22/2026
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 |
|---|---|---|---|---|---|---|---|
| 2017-12-04 | 331-237-5XXX | 5000–5999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2017-11-08 | 331-237-1XXX | 1000–1999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2017-11-08 | 331-237-2XXX | 2000–2999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2017-11-08 | 331-237-3XXX | 3000–3999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2017-11-08 | 331-237-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2017-05-03 | 331-757-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | LEMONT | IL |
| 2016-03-21 | 331-775-9XXX | 9000–9999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | DOWNERSGRV | IL |
| 2015-10-30 | 331-998-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | DOWNERSGRV | IL |
| 2015-09-09 | 331-321-2XXX | 2000–2999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | AURORA | IL |
| 2014-12-30 | 331-701-3XXX | 3000–3999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2014-06-13 | 331-702-6XXX | 6000–6999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2013-10-25 | 331-702-3XXX | 3000–3999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2013-10-25 | 331-702-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2013-10-25 | 331-702-5XXX | 5000–5999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2013-06-21 | 331-803-3XXX | 3000–3999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | LEMONT | IL |
| 2013-05-03 | 331-777-8XXX | 8000–8999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | DOWNERSGRV | IL |
| 2013-02-21 | 331-251-2XXX | 2000–2999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | DOWNERSGRV | IL |
| 2012-11-15 | 331-208-6XXX | 6000–6999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | AURORA | IL |
| 2012-11-15 | 331-208-7XXX | 7000–7999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | AURORA | IL |
| 2012-11-14 | 331-777-6XXX | 6000–6999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | DOWNERSGRV | IL |
| 2012-06-19 | 331-777-3XXX | 3000–3999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | DOWNERSGRV | IL |
| 2012-04-06 | 331-212-3XXX | 3000–3999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | AURORA | IL |
| 2011-02-24 | 331-457-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2010-02-22 | 331-333-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2009-07-16 | 331-333-7XXX | 7000–7999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | NAPERVILLE | IL |
| 2009-03-12 | 331-465-0XXX | 0000–0999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 7229 | W CHICAGO | IL |
| 2008-12-02 | 331-465-7XXX | 7000–7999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 7229 | W CHICAGO | IL |
| 2008-10-24 | 331-643-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | AURORA | IL |
| 2008-08-26 | 331-462-1XXX | 1000–1999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL | 7196 | LOMBARD | IL |
Source: NANPA Thousands Block Assignment Report (All Regions, Public), file date 09/22/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.