820 phone number You can connect with customers in area code 820's major city, Oxnard, California, with a population of 202,063. The area code also covers: Ventura, San Luis Obispo and Santa Barbara Counties. With an increasing demand for new phone numbers, area code 820 is an overlay of area code 805.

The first three digits of a phone number in the United States are known as the area code. The area code is used to identify a geographic region. You can use an online area code lookup tool or a phone book to find out which state or county a particular area code belongs to.

A telephone prefix, also called an exchange code or central office code, is a three-digit code that identifies a much smaller region within an area code. The prefix can refer to a specific city or a section of a city. The telephone prefix is the second 3 digits in a 10-digit phone number.