Located in the Central (GMT -06:00) time zone. Area code 779 serves the state of Illinois. This area code was assigned on February 6th, 2004. On March 17th, 2007 it went into service. 779 is a General Purpose Code. 779 service area does overlap with 815 area codes. Dialing pattern for local calls within the same NPA (area code) is 1+10D.