707-1764-26 is part of a 10-digit phone number associated with Concord, California. Concord is a city in Contra Costa County, California, located just east of the San Francisco Bay. The 707 area code was created in 1991 as a split from the 415 area code and covers most of Marin, Napa, Sonoma, and Mendocino counties. The 1764 portion of the phone number is the exchange code for the area. The last four digits, 26, are used to identify the specific telephone number being called.