858
Area code
CA
United States geographic area code, in service since 1999-06-12. Part of the 619/858 overlay complex — ten-digit dialing required.
Statusin service
Introduced1999-06-12
JurisdictionCA, US
Local dialing1+10D
Time zonePacific
Last verified2026-09-17
Utilization 72.9% of assignable prefixes assigned
As of 09/17/2026
0%577 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 2001-02-15, most recent 2026-09-14.
Area codes serve rate-center geographies, not municipal boundaries. “CA” identifies the jurisdiction, not an exact city footprint.
Top assignees
Ranked by assigned prefixes · initial assignee ≠ current carrier| Rank | Assignee | Prefixes | Share |
|---|---|---|---|
| 01 | PACIFIC BELL | 152 | 26.3% |
| 02 | NEW CINGULAR WIRELESS PCS, LLC | 50 | 8.7% |
| 03 | T-MOBILE USA, INC. | 44 | 7.6% |
| 04 | FRACTEL, LLC | 35 | 6.1% |
| 05 | ONVOY, LLC - CA | 34 | 5.9% |
| 06 | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA | 32 | 5.5% |
| 07 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA | 31 | 5.4% |
| 08 | TELEPORT COMMUNICATIONS AMERICA, LLC - CA | 26 | 4.5% |
| 09 | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 24 | 4.2% |
| 10 | LEVEL 3 TELECOM OF CALIFORNIA, LP - CA | 20 | 3.5% |
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- 1999-06-12Area code 858 entered service (created from 619).
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2017-05-18 | PL-507 ↗ | NPA 619 and 858 Boundary Elimination Overlay (California) |
| 1998-06-30 | PL-128 ↗ | NANP-Phased three-way split of 619 (California) Numbering Plan Area (NPA) with 858 & 935 NPAs |