Greenwich, CT is currently using an area code overlay in which area codes 203 and 475 serve the same geographic area. Ten digit dialing (area code + seven digit number) is necessary because two different homes in the same geographic area can have the same seven digit phone number but each would have a different area code. The area code overlay which is in use today was put into service on December 12, 2009. Area code 203 originally covered the entire state of Connecticut, including when it was established in 1947.
In addition to Greenwich, CT details view area codes 203 and 475 and Connecticut area codes.
Greenwich, CT is located in Fairfield County and observes the Eastern Time Zone. View our Times by Area Code tool.