NumberResearch Membership · Data 09/19/2026

Recent thousands-block assignments

0 blocks assigned in the last 30 days · from the daily NANPA thousands-block report, 09/19/2026

Full prefixes (NXX) Thousands-blocks (1,000-number pools)

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 231
MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 25
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
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Recent thousands-block assignments
AssignedThousands-blockLast 4 digitsStatusAssigneeOCNRate centerState
2021-05-17 231-743-8XXX 8000–8999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 MARION MI
2020-06-29 231-216-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 FRANKFORT MI
2020-06-29 231-280-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 MANCELONA MI
2020-06-29 231-484-5XXX 5000–5999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 EASTJORDAN MI
2020-06-02 231-289-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 CHARLEVOIX MI
2018-04-06 231-624-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 KALKASKA MI
2016-06-13 231-508-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 ONEKAMA MI
2016-02-12 231-259-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 SHELBY MI
2016-02-12 231-465-8XXX 8000–8999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 REED CITY MI
2014-06-03 231-375-2XXX 2000–2999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 MUSKEGON MI
2012-11-08 231-497-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 BOYNE CITY MI
2012-11-08 231-498-8XXX 8000–8999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 ELK RAPIDS MI
2012-11-06 231-292-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 WHITEHALL MI
2012-11-06 231-594-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 HART MI
2012-11-06 231-681-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 FRUITPORT MI
2012-11-06 231-853-1XXX 1000–1999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 RAVENNA MI
2011-04-12 231-480-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 LUDINGTON MI
2010-07-09 231-597-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 CHEBOYGAN MI
2010-07-09 231-794-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 MANISTEE MI
2009-09-04 231-267-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 WILLIAMSBG MI
2006-03-10 231-683-2XXX 2000–2999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 MUSKEGON MI
2005-08-03 231-225-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 FREMONT MI
2005-08-03 231-408-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 BIG RAPIDS MI
2005-08-03 231-577-5XXX 5000–5999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 CADILLAC MI
2005-08-03 231-753-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 PETOSKEY MI

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.