The 663 area code serves the same geographic territory as the 626 area code. This region is located to the east of Downtown Los Angeles and includes a vibrant and diverse collection of cities and communities.
Key Cities and Communities Covered
Some of the prominent cities and communities within the 626 and 663 area code region include:
- Pasadena
- El Monte
- West Covina
- Alhambra
- Arcadia
- Monrovia
- Baldwin Park
- Covina
This area is known for its rich history, cultural landmarks like the Rose Bowl stadium, and significant educational institutions.
Why Was the 663 Area Code Created?

The introduction of the 663 area code was a necessary measure to address the growing demand for telephone numbers in the region.
The Need for a New Area Code
The 626 area code, which was first put into service in 1997, was projected to exhaust its available supply of prefixes and phone numbers. To ensure a continuous supply of numbers for new residents and businesses, the California Public Utilities Commission (CPUC) approved an overlay plan. This plan introduced the 663 area code to serve the same region, effectively doubling the number of available phone numbers.
Implementation of the Overlay
The 663 area code officially went into effect on June 10, 2021. From this date forward, new telephone lines and services in the 626 territory could be assigned a number with the 663 area code.
How Does the 663 Area Code Affect Local Dialing?
The implementation of an overlay area code significantly changes how local calls are dialed.
Mandatory 10-Digit Dialing
To ensure calls are routed correctly within the overlay region, all callers are required to use 10-digit dialing. This means that for all local calls, you must dial the area code followed by the seven-digit telephone number. This applies to calls made within the same area code as well as calls between the 626 and 663 area code. This change was implemented to accommodate the coexistence of two area codes in the same geographic area.