What is a 201 code?

Area codes 201 and 551 are telephone area codes in the North American Numbering Plan in the U.S. state of New Jersey. Area code 201 was the area code assigned to the entire state of New Jersey in 1947, when the North American area code system was formulated.

For More Information Please Refer: https://en.wikipedia.org/wiki/Area_codes_201_and_551