After the conclusion of a hearing the Commission shall make and file its findings and order with its opinion, if any. Its findings shall be in sufficient detail to enable a court on review to determine the controverted question presented by the proceeding and whether proper weight was given to the evidence. A copy of such order, certified under the seal of the Commission, shall be served either personally or by registered mail upon the person, corporation or telephone utility against whom it runs, or his or its attorney, and notice thereof shall be given either personally or by mail to the other parties to the proceedings or their attorneys.