Section 13
SEC. 13. The grantee may, with the approval of the Philippine Legislature first had, lease, grant, sell, convey, or give in usufruct this franchise and any property and rights acquired thereunder to any person or corporation: Provided, That for the purpose of such lease, grant, sale, conveyance, or giving in usufruct, it shall be necessary to file in the office of the Secretary of Commerce and Communications an agreement in writing by which the person or corporation in whose favor such lease, grant, sale, conveyance, or giving in usufruct is made, shall bind itself to comply with, and accept the franchise subject to all existing terms and conditions.