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 520
QWEST CORPORATION 201
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 104
T-MOBILE USA, INC. 84
NEW CINGULAR WIRELESS PCS, LLC 53
ONVOY, LLC - AZ 47
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
Clear Download CSV ↓
Recent NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
2015-07-23 520-719 0–9 XXXall 10 · 6 holders which blocks → BANDWIDTH.COM CLEC, LLC - AZ 587F TUCSON AZ
2015-06-22 520-348 0–9 XXXall 10 · 5 holders which blocks → CENTURYLINK COMMUNICATIONS, LLC 508J WILLCOX AZ
2015-06-05 520-595 0–9 XXXall 10 · 5 holders which blocks → CENTURYLINK COMMUNICATIONS, LLC 508J BENSON AZ
2015-05-13 520-485 0–9 XXXwhole prefix which blocks → BANDWIDTH.COM CLEC, LLC - AZ 587F TUCSON AZ
2015-04-17 520-639 0–9 XXXall 10 · 5 holders which blocks → CENTURYLINK COMMUNICATIONS, LLC 508J TUCSON AZ
2015-04-07 520-635 0–9 XXXall 10 · 7 holders which blocks → T-MOBILE USA, INC. 6529 CASAGRANDE AZ
2015-03-10 520-815 0–9 XXXall 10 · 2 holders which blocks → BANDWIDTH.COM CLEC, LLC - AZ 587F TUCSON AZ
2015-02-26 520-500 0–9 XXXall 10 · 3 holders which blocks → ONVOY, LLC - AZ 630E TUCSON AZ
2015-01-28 520-800 0–9 XXXall 10 · 3 holders which blocks → ONVOY, LLC - AZ 630E TUCSON AZ
2015-01-19 520-528 0–9 XXXall 10 · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 TUCSON AZ
2015-01-19 520-848 0–9 XXXall 10 · 4 holders which blocks → METROPCS, INC. 5562 TUCSON AZ
2015-01-02 520-965 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2014-12-23 520-809 0–9 XXXall 10 · 5 holders which blocks → INTRADO COMMUNICATIONS, LLC 890G TUCSON AZ
2014-12-15 520-599 0–9 XXXwhole prefix which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 TUCSON AZ
2014-10-30 520-276 0–9 XXXwhole prefix which blocks → BANDWIDTH.COM CLEC, LLC - AZ 587F TUCSON AZ
2014-10-24 520-658 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2014-10-17 520-729 0–9 XXXall 10 · 7 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 TUCSON AZ
2014-10-09 520-389 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 TUCSON AZ
2014-09-23 520-283 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2014-09-22 520-788 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 CASAGRANDE AZ
2014-08-28 520-278 0–9 XXXall 10 · 3 holders which blocks → METROPCS, INC. 5562 TUCSON AZ
2014-08-19 520-257 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2014-08-19 520-273 0–9 XXXall 10 · 2 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 TUCSON AZ
2014-06-24 520-359 0–9 XXXall 10 · 7 holders which blocks → METROPCS, INC. 5562 TUCSON AZ
2014-05-14 520-328 0–9 XXXall 10 · 3 holders which blocks → QWEST CORPORATION 9636 TUCSON AZ
2014-04-30 520-448 0–9 XXXall 10 · 4 holders which blocks → PEERLESS NETWORK OF ARIZONA, LLC - AZ 579F TUCSON AZ
2014-04-09 520-539 0–9 XXXwhole prefix which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 TUCSON AZ
2014-02-28 520-447 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLC - AZ 630E TUCSON AZ
2014-02-28 520-775 0–9 XXXall 10 · 2 holders which blocks → BANDWIDTH.COM CLEC, LLC - AZ 587F TUCSON AZ
2014-02-18 520-279 0–9 XXXwhole prefix which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 TUCSON AZ
2014-02-05 520-606 0–9 XXXall 10 · 6 holders which blocks → METROPCS, INC. 5562 TUCSON AZ
2014-01-17 520-428 0–9 XXXall 10 · 2 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 TUCSON AZ
2013-10-24 520-912 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC 6010 TUCSON AZ
2013-09-30 520-645 0–9 XXXall 10 · 5 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 DOUGLAS AZ
2013-08-20 520-210 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLC - AZ 630E TOMBSTONE AZ
2013-06-25 520-213 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CASAGRANDE AZ
2013-04-19 520-499 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2013-03-14 520-268 0–9 XXXall 10 · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 TUCSON AZ
2013-01-11 520-286 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2013-01-11 520-345 0–9 XXXall 10 · 2 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 TUCSON AZ
2013-01-11 520-427 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2012-11-20 520-433 0–9 XXXall 10 · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - AZ 3285 TUCSON AZ
2012-11-16 520-474 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2012-11-05 520-999 0–9 XXXall 10 · 6 holders which blocks → ONVOY, LLC - AZ 630E TUCSON AZ
2012-10-31 520-373 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2012-10-22 520-484 0–9 XXXall 10 · 3 holders which blocks → NUSO, LLC 551G TUCSON AZ
2012-09-24 520-442 0–9 XXXall 10 · 4 holders which blocks → BANDWIDTH.COM CLEC, LLC - AZ 587F BENSON AZ
2012-09-17 520-460 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 TUCSON AZ
2012-09-07 520-355 0–9 XXXall 10 · 2 holders which blocks → BANDWIDTH.COM CLEC, LLC - AZ 587F TUCSON AZ
2012-08-13 520-422 0–9 XXXall 10 · 5 holders which blocks → AT&T - LOCAL 7421 BISBEE AZ

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.