The Commission, for good cause shown, may allow changes in rates without requiring the thirty days’ notice under such conditions as it may prescribe, except that when changes in general schedules of rates and charges are involved, before they may become effective, notice to the public of such proposed changes shall be given by publication thereof once a week for two consecutive weeks in newspapers of general circulation in the territory involved and a hearing held thereon. All such changes shall be immediately indicated upon its schedules by such telephone utility.