What is what area code is 424?

Area code 424 serves the western portion of Los Angeles County, California (https://www.wikiwhat.page/kavramlar/Los%20Angeles%20County,%20California). It is an overlay for area code 310. This means that within the same geographic area, both 310 and 424 area codes can be in use. A mandatory 10-digit dialing (https://www.wikiwhat.page/kavramlar/mandatory%2010-digit%20dialing) is required to make calls, even for local calls within the same area code. This was implemented to alleviate the exhaustion of available phone numbers in the 310 area code.