What is the area code for Stockton CA?

Stockton, California, is in area code +1 209.

Stockton, Indiana, is in area code +1 812.

Stockton, Missouri, is in area code +1 417.

Stockton, Illinois, is in area code +1 815 and overlay area code +1 779.

Stockton, New Jersey, is in area code +1 609.

(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)