623
Area code
AZ
United States geographic area code, in service since 1999-03-01. Part of the 480/602/623 overlay complex — ten-digit dialing required.
Statusin service
Introduced1999-03-01
JurisdictionAZ, US
Local dialing10D
Time zoneMountain
Last verified2026-09-17
Utilization 41.2% of assignable prefixes assigned
As of 09/17/2026
0%326 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 2001-01-18, most recent 2026-08-14.
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 | 97 | 29.8% |
| 02 | T-MOBILE USA, INC. | 39 | 12% |
| 03 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ | 31 | 9.5% |
| 04 | ONVOY, LLC - AZ | 29 | 8.9% |
| 05 | NEW CINGULAR WIRELESS PCS, LLC | 22 | 6.7% |
| 06 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 13 | 4% |
| 07 | COMCAST IP PHONE, LLC | 11 | 3.4% |
| 08 | LEVEL 3 COMMUNICATIONS, LLC - AZ | 10 | 3.1% |
| 09 | TELEPORT COMMUNICATIONS AMERICA, LLC - AZ | 9 | 2.8% |
| 10 | MULTIPLE OCN LISTING | 9 | 2.8% |
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- 1999-03-01Area code 623 entered service (created from 602).
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2021-12-30 | PL-576 ↗ | NPA 480, 602 and 623 Boundary Elimination Overlay (Arizona) |
| 2000-02-24 | PL-216 ↗ | Permissive Dialing Extended for Eleven Central Office Codes in the 602 NPA (Arizona) |
| 1999-07-21 | PL-181 ↗ | Urgent reminder to update networks for the 602 NPA Split in Phoenix, Arizona with the new 623 and 480 NPAs |
| 1999-02-01 | PL-153 ↗ | NANP-Split of the 602 (Arizona) Numbering Plan Area (NPA) and the Addition of the 480 and 623 NPA's |