Located in the Eastern (GMT -05:00) time zone. Area code 201 serves the state of New Jersey. This area code was assigned on January 1st, 1947. On January 1st, 1947 it went into service. 201 is a General Purpose Code. 201 service area does overlap with 551 area codes. Dialing pattern for local calls within the same NPA (area code) is 10D. Calls between the 551 and 201 NPAs may be dialed as 10D.