NumberResearch Membership · Data 09/19/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/19/2026

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 773
ILLINOIS BELL TEL CO 257
T-MOBILE USA, INC. 169
NEW CINGULAR WIRELESS PCS, LLC - IL 84
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 59
MCIMETRO ACCESS TRANSMISSION SERVICES LLC 38
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
2004-12-30 773-530 0–9 XXXall 10 · 3 holders which blocks → COMCAST IP PHONE, LLC 318J CHICGOZN09 IL
2004-12-28 773-540 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2004-11-17 773-503 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2004-10-13 773-494 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2004-10-13 773-512 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2004-09-28 773-499 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2004-09-24 773-366 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2004-09-07 773-318 0–9 XXXwhole prefix which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 CHICGOZN03 IL
2004-09-07 773-414 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2004-07-27 773-688 0–9 XXXall 10 · 3 holders which blocks → RCN TELECOM SERVICES OF ILLINIOS, INC. - IL 8702 CHICGOZN05 IL
2004-07-20 773-600 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2004-06-09 773-387 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2004-05-24 773-537 0–9 XXXall 10 · 3 holders which blocks → FIRST COMMUNICATIONS, LLC 460K CHICGOZN04 IL
2004-05-21 773-565 0–9 XXXall 10 · 3 holders which blocks → FIRST COMMUNICATIONS, LLC 460K CHICGOZN06 IL
2004-03-22 773-310 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2002-10-16 773-715 1XXX2XXX3XXX4XXX5XXX7XXX8XXX which blocks → T-MOBILE USA, INC. 6529 CHICGOZN06 IL
2002-10-16 773-727 8XXX which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2002-10-16 773-817 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2002-08-21 773-934 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2002-08-15 773-807 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN02 IL
2002-08-06 773-870 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN03 IL
2002-07-22 773-814 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2002-05-21 773-759 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2002-04-04 773-510 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2002-03-28 773-983 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2002-03-27 773-655 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2002-03-07 773-677 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN03 IL
2002-01-23 773-704 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2002-01-04 773-426 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2001-11-30 773-615 0XXX1XXX2XXX3XXX4XXX5XXX6XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2001-11-05 773-742 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
2001-10-17 773-610 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN03 IL
2001-09-13 773-750 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN03 IL
2001-09-06 773-875 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN08 IL
2001-08-30 773-744 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN06 IL
2001-08-30 773-865 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN02 IL
2001-08-30 773-895 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2001-08-30 773-936 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN07 IL
2001-08-08 773-837 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN04 IL
2001-07-06 773-858 3XXX4XXX5XXX which blocks → T-MOBILE USA, INC. 6529 CHICGOZN02 IL
2001-06-28 773-757 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN08 IL
2001-05-25 773-791 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN03 IL
2001-05-25 773-844 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN03 IL
2001-05-23 773-931 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN10 IL
2001-04-23 773-781 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 CHICGOZN01 IL
2001-04-23 773-845 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 CHICGOZN01 IL
2001-04-19 773-842 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2001-04-16 773-323 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 CHICGOZN02 IL
2001-04-16 773-333 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 CHICGOZN02 IL
2001-04-16 773-400 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 CHICGOZN02 IL

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.