Area code

CA

United States geographic area code, in service since 2025-03-26. Part of the 357/559 overlay complex — ten-digit dialing required.

Split from 559. Overlaid with 559 .

Statusin service

Introduced2025-03-26

JurisdictionCA, US

Local dialing1+10D

Time zonePacific

Last verified2026-09-17

Utilization 1.8% of assignable prefixes assigned As of 09/17/2026

0%14 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 —, most recent —.

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

Largest initial assignees in area code 357
Rank	Assignee	Prefixes	Share
01	MULTIPLE OCN LISTING	14	100%

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

2024-02-06 NPA 357 to Overlay NPA 559 (California) overlay
2025-03-26Area code 357 entered service (created from 559).

Planning letters & orders

Primary documents

NANPA planning letters for area code 357
Date	Document	Subject
2024-02-06	PL-624 ↗	NPA 357 to Overlay NPA 559 (California)

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