NumberResearch Membership · Data 09/20/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/20/2026

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

The Code holder is who opened each NPA-NXX prefix — not necessarily who holds the numbers. A prefix is 10,000 numbers, but under pooling its ten 1,000-number blocks are handed out individually, often to different carriers; the code holder may hold only one block, or none. The Thousands-blocks column shows how the ten blocks are really split — click which blocks → to see who holds each 1,000-number block and its last-4-digit range. Assignments are initial assignments; the current serving carrier may differ due to portability.

Most active assignees, all time — NPA 312
ILLINOIS BELL TEL CO 334
NEW CINGULAR WIRELESS PCS, LLC - IL 82
T-MOBILE USA, INC. 64
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 54
SPOK, INC. 33
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 NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
2016-06-17 312-826 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-05-04 312-586 0–9 XXXall 10 · 3 holders which blocks → ONVOY, LLC 224C CHICGOZN01 IL
2016-03-17 312-825 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-02-03 312-366 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN01 IL
2016-02-01 312-383 0–9 XXXall 10 · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN01 IL
2016-01-11 312-539 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-01-11 312-838 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-12-21 312-858 0–9 XXXall 10 · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - IL 6115 CHICGOZN01 IL
2015-12-04 312-868 0–9 XXXall 10 · 2 holders which blocks → BANDWIDTH.COM CLEC, LLC - IL 984E CHICGOZN01 IL
2015-09-25 312-549 0–9 XXXall 10 · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN01 IL
2015-09-22 312-885 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-09-17 312-734 0–9 XXXall 10 · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN01 IL
2015-09-03 312-837 0–9 XXXall 10 · 6 holders which blocks → COMCAST IP PHONE, LLC 318J CHICGOZN01 IL
2015-08-28 312-871 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-07-21 312-358 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-06-26 312-468 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-06-26 312-471 0–9 XXXall 10 · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 CHICGOZN01 IL
2015-06-26 312-536 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-06-25 312-889 0–9 XXXall 10 · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN01 IL
2015-06-25 312-989 0–9 XXXall 10 · 4 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN01 IL
2015-06-01 312-722 0–9 XXXall 10 · 2 holders which blocks → PAETEC ITEL, LLC 829J CHICGOZN01 IL
2015-05-22 312-874 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-05-08 312-778 0–9 XXXall 10 · 3 holders which blocks → ONVOY, LLC 224C CHICGOZN01 IL
2015-04-16 312-767 0–9 XXXwhole prefix which blocks → BANDWIDTH.COM CLEC, LLC - IL 984E CHICGOZN01 IL
2015-03-23 312-897 0–9 XXXall 10 · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 CHICGOZN01 IL
2015-02-09 312-517 0–9 XXXall 10 · 7 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 CHICGOZN01 IL
2014-12-08 312-934 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-11-20 312-792 0–9 XXXall 10 · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 CHICGOZN01 IL
2014-11-18 312-966 0–9 XXXall 10 · 4 holders which blocks → METROPCS, INC. 5562 CHICGOZN01 IL
2014-11-12 312-883 0–9 XXXwhole prefix which blocks → BANDWIDTH.COM CLEC, LLC - IL 984E CHICGOZN01 IL
2014-11-10 312-313 0–9 XXXwhole prefix which blocks → ONVOY, LLC 224C CHICGOZN01 IL
2014-10-27 312-487 0–9 XXXall 10 · 4 holders which blocks → METROPCS, INC. 5562 CHICGOZN01 IL
2014-10-07 312-982 0–9 XXXall 10 · 3 holders which blocks → COMCAST IP PHONE, LLC 318J CHICGOZN01 IL
2014-09-29 312-956 0–9 XXXall 10 · 2 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN01 IL
2014-09-25 312-937 0–9 XXXall 10 · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 CHICGOZN01 IL
2014-09-15 312-975 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-08-22 312-483 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-08-22 312-522 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-08-22 312-866 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-08-19 312-785 0–9 XXXwhole prefix which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN01 IL
2014-08-12 312-877 0–9 XXXall 10 · 3 holders which blocks → AT&T ENTERPRISES, LLC 516C CHICGOZN01 IL
2014-08-12 312-995 0–9 XXXall 10 · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN01 IL
2014-08-12 312-998 0–9 XXXall 10 · 2 holders which blocks → CENTURYLINK COMMUNICATIONS, LLC 508J CHICGOZN01 IL
2014-08-07 312-967 0–9 XXXwhole prefix which blocks → BANDWIDTH.COM CLEC, LLC - IL 984E CHICGOZN01 IL
2014-07-01 312-248 0–9 XXXall 10 · 4 holders which blocks → METROPCS, INC. 5562 CHICGOZN01 IL
2014-05-12 312-763 0–9 XXXall 10 · 5 holders which blocks → COMCAST IP PHONE, LLC 318J CHICGOZN01 IL
2014-05-06 312-690 0–9 XXXall 10 · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - IL 6115 CHICGOZN01 IL
2014-05-01 312-971 0–9 XXXwhole prefix which blocks → BANDWIDTH.COM CLEC, LLC - IL 984E CHICGOZN01 IL
2014-03-20 312-478 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-03-12 312-843 0–9 XXXall 10 · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN01 IL

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.