657
Area code
CA
United States geographic area code, in service since 2008-09-23. Part of the 657/714 overlay complex — ten-digit dialing required. NANPA has flagged this area code for relief planning.
Statusin service
Introduced2008-09-23
JurisdictionCA, US
Local dialing1+10D
Time zonePacific
ReliefPlanning
Last verified2026-09-17
Utilization 89.4% of assignable prefixes assigned
As of 09/17/2026
0%708 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 2008-08-08, most recent 2026-09-09.
Relief planning is under way for area code 657.
No planning letter has been issued yet for this cycle — this page will be updated the day one is published. Subscribe to the change-event feed to be notified.
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 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA | 364 | 51.4% |
| 02 | T-MOBILE USA, INC. | 74 | 10.5% |
| 03 | NEW CINGULAR WIRELESS PCS, LLC | 47 | 6.6% |
| 04 | FRACTEL, LLC | 40 | 5.6% |
| 05 | BANDWIDTH.COM CLEC, LLC - CA | 35 | 4.9% |
| 06 | ONVOY, LLC - CA | 33 | 4.7% |
| 07 | LEVEL 3 COMMUNICATIONS, LLC - CA | 16 | 2.3% |
| 08 | PEERLESS NETWORK OF CALIFORNIA, LLC - CA | 14 | 2% |
| 09 | TWC IP ENABLED SERVICES, LLC | 13 | 1.8% |
| 10 | TON80 COMMUNICATIONS, LLC | 9 | 1.3% |
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- 2007-10-03 NPA 657 to Overlay NPA 714 (California)
- 2008-09-23Area code 657 entered service (created from 714).
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2007-10-03 | PL-368 ↗ | NPA 657 to Overlay NPA 714 (California) |
| 2000-01-14 | PL-206 ↗ | Overlays Suspended in the 408, 415, 510, 650, 714 & 909 NPAs |
| 1999-04-22 | PL-169 ↗ | NANP Overlay of 714 NPA with 657 NPA in Southern California |