NumberResearch Membership · Data 09/25/2026

Recent thousands-block assignments

0 blocks assigned in the last 30 days · from the daily NANPA thousands-block report, 09/25/2026

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 443
MCIMETRO ACCESS TRANSMISSION SERVICES LLC 103
MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 85
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
2023-02-08 443-701-6XXX 6000–6999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ARBUTUS MD
2021-09-28 443-485-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ELKTON MD
2021-04-20 443-514-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 CATONSVL MD
2020-06-30 443-491-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 PARKTON MD
2020-05-26 443-620-2XXX 2000–2999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 WATERLO238 MD
2019-07-31 443-947-6XXX 6000–6999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 PERRYVILLE MD
2018-06-05 443-782-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 ANNAPOLIS MD
2018-01-10 443-441-5XXX 5000–5999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 GLENWOOD MD
2017-11-09 443-754-6XXX 6000–6999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 SALISBURY MD
2017-07-10 443-731-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 PT DEPOSIT MD
2017-03-16 443-914-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 WORTHINGTN MD
2016-02-19 443-234-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 SNOW HILL MD
2015-08-20 443-746-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 EASTON MD
2015-07-31 443-448-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 DENTON MD
2015-01-16 443-776-5XXX 5000–5999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 ELKRIDGE MD
2014-11-05 443-707-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 ABERDEEN MD
2014-06-02 443-753-2XXX 2000–2999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 WATERLO236 MD
2013-08-28 443-873-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 BALTIMORE MD
2013-08-13 443-952-5XXX 5000–5999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 WESTMINSTR MD
2013-07-26 443-558-2XXX 2000–2999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2013-06-25 443-917-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 COLUMBIA MD
2013-05-20 443-720-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2012-12-20 443-713-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 GLENBURNIE MD
2012-12-04 443-720-5XXX 5000–5999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2012-11-29 443-720-1XXX 1000–1999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2012-11-29 443-720-2XXX 2000–2999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2012-11-13 443-855-0XXX 0000–0999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2012-09-17 443-275-6XXX 6000–6999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 TOWSON MD
2012-04-16 443-741-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 COLUMBIA MD
2012-04-05 443-567-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 BEL AIR MD
2011-12-27 443-437-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 POCOMOKE MD
2011-12-08 443-214-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 ANNAPOLIS MD
2011-11-18 443-470-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 TOWSON MD
2011-10-25 443-860-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 CATONSVL MD
2011-10-25 443-931-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 BALTIMORE MD
2011-10-05 443-210-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 SALISBURY MD
2011-06-02 443-475-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 BALTIMORE MD
2011-06-02 443-475-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 BALTIMORE MD
2011-05-17 443-289-2XXX 2000–2999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 WESTMINSTR MD
2011-05-17 443-289-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 WESTMINSTR MD
2011-04-01 443-330-6XXX 6000–6999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 COCKEYSVL MD
2011-03-31 443-741-3XXX 3000–3999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 COLUMBIA MD
2011-01-06 443-860-5XXX 5000–5999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 CATONSVL MD
2010-12-16 443-860-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 CATONSVL MD
2010-11-09 443-319-8XXX 8000–8999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 COLUMBIA MD
2010-10-08 443-249-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD 7228 STEVENSVL MD
2010-10-08 443-403-4XXX 4000–4999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2010-10-08 443-403-5XXX 5000–5999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2010-10-08 443-403-6XXX 6000–6999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD
2010-10-08 443-403-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ABERDEEN MD

Source: NANPA Thousands Block Assignment Report (All Regions, Public), file date 09/25/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.