---
title: "Area code 520: Arizona, United States"
url: "https://lookvalid.com/area-code/520.md"
canonical_url: "https://lookvalid.com/area-code/520"
last_updated: "2026-10-23"
type: "reference"
summary: "Area code 520 serves Arizona, United States. Number formats, numbering rules, a live phone validator and the other codes in Arizona."
---

# Area code 520: Arizona, United States

Area code 520 serves Arizona, United States. Number formats, numbering rules, a live phone validator and the other codes in Arizona.

NANPA lists 694 central office codes (prefixes) in use in area code 520, held by 50 holders across 37 rate centers.
The largest rate center is TUCSON, with 399 prefixes (57%).
Qwest holds the most prefixes, 200 (29%). 70% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
The FCC unwanted-call data has 3,985 complaints on file for 3,153 numbers in 520, most often filed as "Unwanted Calls". These are consumer reports, not findings.

## Facts

- In service since: 1995-03-19
- Time zone: Mountain (M)
- Prefixes in use: 694
- Pooled prefixes: 487 (70%)
- Rate centers: 37
- Companies holding prefixes: 50
- Assignment dates on file: 2001-01-08 to 2026-04-03 (346 prefixes)
- ZIP codes in its places: 102

## Rate centers

| Rate center | Prefixes | Share |
| --- | --- | --- |
| TUCSON | 399 | 57% |
| SIERRAVIST | 70 | 10% |
| CASAGRANDE | 67 | 10% |
| NOGALES | 31 | 4% |
| WILLCOX | 18 | 3% |
| BENSON | 12 | 2% |
| BISBEE | 9 | 1% |
| DOUGLAS | 9 | 1% |
| 29 other rate centers | 79 | 11% |

## Carriers

| Holder | Prefixes | Share |
| --- | --- | --- |
| Qwest | 200 | 29% |
| Verizon Wireless | 104 | 15% |
| T-Mobile USA | 84 | 12% |
| New Cingular Wireless PCS | 53 | 8% |
| Onvoy | 47 | 7% |
| Mcimetro Access Transmission Services | 26 | 4% |
| 44 other carriers | 180 | 26% |

A prefix holder is the company a code was assigned to, not necessarily a number's current carrier, because numbers can be ported to another company.

## History

- 1947-01-01: Area code 602, named as the parent of 520 in the NANPA report, was in service.
- 1995-03-19: Area code 520 went into service.
- 2001-06-23: Area code 928 went into service and names 520 as its parent.

## Nearest area codes

The area codes closest to 520, measured between the centers of the ZIP code places they serve, are 480 (about 75 miles), 602 (about 75 miles), 623 (about 75 miles), 928 (about 137 miles) and 915 (about 293 miles).

## ZIP codes

102 ZIP codes fall in places that have a rate center in this area code. The places with the most are Tucson, AZ (54 ZIP codes), Flagstaff, AZ (6 ZIP codes) and Prescott, AZ (6 ZIP codes). A ZIP code and an area code are unrelated systems, so a ZIP code can sit in more than one area code and an area code spans many ZIP codes.

## Complaints on file

3,985 complaints for 3,153 numbers. Numbers whose latest complaint falls in each year:

- 2023: 211
- 2024: 253
- 2025: 181

## Questions

### Where is area code 520?

NANPA assigns area code 520 to Arizona, United States.

### In which state does area code 520 sit?

Arizona. 520 is one of 5 area codes the NANPA table assigns to the state.

### Which places does area code 520 cover?

The places with the most ZIP codes among the rate centers in 520 are Tucson, AZ, Flagstaff, AZ and Prescott, AZ. The rate center list on this page shows all of them.

### Who owns area code 520?

NANPA assigns area codes. Within 520, Qwest holds the most prefixes, 200 prefixes or 29%.

### Which time zone does 520 use?

The NANPA NPA report lists the time zone for 520 as Mountain (M).

### What year did 520 enter service?

The NANPA NPA report gives an in-service date of 1995-03-19, so 520 has been in use since 1995.

### Does area code 520 have an overlay?

The NANPA NPA report lists no other area code in an overlay with 520.

### Which area codes are nearest to 520?

The area codes closest to 520, measured between the centers of the ZIP code places they serve, are 480 (about 75 miles), 602 (about 75 miles), 623 (about 75 miles), 928 (about 137 miles) and 915 (about 293 miles).

### How many prefixes does area code 520 have?

NANPA's report dated 2026-10-17 lists 694 prefixes in service in 520, spread over 37 rate centers and 50 holders.

### Are there complaints about 520 numbers?

The FCC data on file has 3,985 complaints for 3,153 numbers in 520. They are unverified consumer reports. A number with no complaints on file is not proven safe.

Sources: NANPA central office code report dated 2026-10-17; NANPA NPA report dated 2026-10-18; FCC unwanted-call complaints, data fetched 2026-10-17; ZIP code places from GeoNames (CC BY 4.0).