The terminator goes to Sarah's mom's cabin, hoping Sarah will make contact there. He gets the location from Sarah's address book, which lists it as being in Big Bear. This is in San Bernardino County in southern California. When Sarah calls & gives the phone number of the motel, she specifies that it's in the 408 area code. At the time this film was made, that area code covered the central coast of California from Monterey to north of San Jose. In order to call the hotel from Big Bear, the terminator would need to dial 1-408 then the number. But instead, he just dials the number without area code.