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
— 773-402 8XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN01 IL
— 773-403 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
— 773-404 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 CHICGOZN04 IL
— 773-405 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 CHICGOZN01 IL
— 773-406 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN07 IL
— 773-407 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
— 773-409 0XXX1XXX2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN02 IL
— 773-410 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN02 IL
— 773-411 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX IL
— 773-412 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
— 773-413 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN05 IL
— 773-415 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 CHICGOZN01 IL
— 773-416 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 773-417 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → COMCAST IP PHONE, LLC 318J CHICGOZN05 IL
— 773-418 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
— 773-419 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 773-420 6XXX7XXX8XXX9XXX · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN07 IL
— 773-421 none assigned yet which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 CHICGOZN01 IL
— 773-422 none assigned yet which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 CHICGOZN01 IL
— 773-423 2XXX6XXX7XXX · 2 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 CHICGOZN02 IL
— 773-424 2XXX9XXX · 2 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN08 IL
— 773-425 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
— 773-427 none assigned yet which blocks → ILLINOIS BELL TEL CO 9329 CHICGOZN03 IL
— 773-428 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN01 IL
— 773-429 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 CHICGOZN10 IL
— 773-430 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
— 773-432 0XXX1XXX4XXX5XXX7XXX8XXX · 4 holders which blocks → FIRST COMMUNICATIONS, LLC 460K CHICGOZN08 IL
— 773-433 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN02 IL
— 773-434 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 CHICGOZN08 IL
— 773-435 4XXX5XXX6XXX8XXX9XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 CHICGOZN04 IL
— 773-436 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 CHICGOZN08 IL
— 773-437 0XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 CHICGOZN09 IL
— 773-438 not yet reported which blocks → SPOK, INC. 6630 CHICGOZN01 IL
— 773-439 0XXX1XXX2XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → RCN TELECOM SERVICES OF ILLINIOS, INC. - IL 8702 CHICGOZN03 IL
— 773-440 0–9 XXXall 10 · 2 holders which blocks → METROPCS, INC. 5562 CHICGOZN10 IL
— 773-442 2XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL 7196 CHICGOZN02 IL
— 773-443 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 773-444 7XXX8XXX9XXX which blocks → ILLINOIS BELL TEL CO 9329 CHICGOZN03 IL
— 773-445 not yet reported which blocks → ILLINOIS BELL TEL CO 9329 CHICGOZN10 IL
— 773-446 0XXX2XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - IL 6115 CHICGOZN06 IL
— 773-447 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 773-449 0XXX1XXX2XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → RCN TELECOM SERVICES OF ILLINIOS, INC. - IL 8702 CHICGOZN09 IL
— 773-450 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN01 IL
— 773-451 5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → ILLINOIS BELL TEL CO 9329 CHICGOZN07 IL
— 773-452 none assigned yet which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 CHICGOZN01 IL
— 773-453 2XXX4XXX5XXX6XXX7XXX8XXX9XXX which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 CHICGOZN11 IL
— 773-454 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN03 IL
— 773-455 0XXX1XXX2XXX3XXX4XXX5XXX · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - IL 7196 CHICGOZN11 IL
— 773-456 not yet reported which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHICGOZN03 IL
— 773-457 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN07 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.