Section 5
SEC. 5. All telephone lines and system for transmission of messages and signals owned, maintained, or operated by the grantee, its successors or assigns, shall be operated and maintained at all times in a satisfactory manner, and it shall be the further duty of said grantee, its successors or assigns, whenever required to do so by the Public Service Commission, to modify improve and change such telephone system or system for the transmission of messages and signals by means of electricity in such manner and to such extent as the progress of science and improvements in the method of transmission of messages and signals by means of electricity may make reasonable and proper.