Area code 650 is a telephone area code in the North American Numbering Plan (NANP) for the San Francisco Bay Area in the U.S. state of California. It was split from area code 415 on August 2, 1997, and includes most of San Mateo County (except the northernmost portion), part of San Francisco, and the northwestern portion of Santa Clara County including Palo Alto, Mountain View, and Los Altos. Prior to October 2021, area code 650 had telephone numbers assigned for the central office code 988. In 2020, 988 was designated nationwide as a dialing code for the National Suicide Prevention Lifeline, which created a conflict for exchanges that permit seven-digit dialing. This area code was therefore scheduled to transition to ten-digit dialing by October 24, 2021. Service area San Mateo County Atherton Belmont Broadmoor Burlingame Colma Daly City (small portion in 415) East Palo Alto El Granada Emerald Lake Hills Foster City Half Moon Bay Highlands-Baywood Park Hillsborough Kings Mountain La Honda Ladera Loma Mar Los Trancos Woods Menlo Park Middleton Tract Millbrae Montara Moss Beach North Fair Oaks Pacifica Pescadero Portola Valley Princeton-by-the-Sea Redwood City San Bruno San Carlos San Gregorio San Mateo Sky Londa South San Francisco West Menlo Park Woodside Santa Clara County Los Altos Los Altos Hills Loyola Mountain View Palo Alto Stanford Sunnyvale (western edge) San Francisco County San Francisco References External links List of exchanges from AreaCodeDownload.com, 650 Area Code 650 650 Northern California 1997 introductions