520
Area code
Statusin service
Introduced1995-03-19
JurisdictionAZ, US
Local dialing10D
Time zoneMountain
Last verified2026-09-17
Utilization 89.5% of assignable prefixes assigned
As of 09/17/2026
0%709 of ~792 assignable NXX values (200–999 excl. N11)100%
Prefix-level assignment does not equal number-level exhaustion; thousands-block pooling extends capacity. First assignment on record 2001-01-08, most recent 2026-04-03.
Area codes serve rate-center geographies, not municipal boundaries. “AZ” identifies the jurisdiction, not an exact city footprint.
Top assignees
Ranked by assigned prefixes · initial assignee ≠ current carrier| Rank | Assignee | Prefixes | Share |
|---|---|---|---|
| 01 | QWEST CORPORATION | 201 | 28.3% |
| 02 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ | 104 | 14.7% |
| 03 | T-MOBILE USA, INC. | 84 | 11.8% |
| 04 | NEW CINGULAR WIRELESS PCS, LLC | 53 | 7.5% |
| 05 | ONVOY, LLC - AZ | 47 | 6.6% |
| 06 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - AZ | 24 | 3.4% |
| 07 | LEVEL 3 COMMUNICATIONS, LLC - AZ | 17 | 2.4% |
| 08 | BANDWIDTH.COM CLEC, LLC - AZ | 17 | 2.4% |
| 09 | TELEPORT COMMUNICATIONS AMERICA, LLC - AZ | 14 | 2% |
| 10 | LEVEL 3 TELECOM OF ARIZONA, LLC - AZ | 12 | 1.7% |
Important: these are initial assignees from NANPA CO-code records — the carrier a prefix was originally assigned to. Because of number portability, the current serving carrier of any individual number may differ.
Change history
Recorded events for this NPA- 1995-03-19Area code 520 entered service (created from 602).
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2021-01-08 | PL-556 ↗ | Transition to 10-digit dialing (for 988 as 3-digit access to National Suicide Prevention Lifeline) – supersedes PL-544 |
| 2020-08-17 | PL-544 ↗ | Transition to 10-digit dialing (for 988 as 3-digit access to National Suicide Prevention Hotline |
| 1994-01-21 | IL-94-01-030 ↗ | NANP-SPLIT OF 602 (ARIZONA) NUMBERING PLAN AREA (NPA) |