Area code and exchange code is assigned to every constituent of city in the United States. The area and exchange codes of the telephone can be used to find information about a region. Area code 620 and exchange code 836 is assigned to Gridley. The latitude and longitude corresponding to 38.09 and -95.88 can be used to find an area on the map. United Telephone Company Of Easternoperates most of the land lines in United States.