Section 15
SEC. 15. The grantee herein shall not, without prior authorization of the Philippine Legislature, lease, grant, sell, convey, or give in usufruct this franchise and all property and rights acquired thereunder to any person or corporation: Provided, That for the purpose of the lease, granting, 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 blind himself to comply with all the terms and conditions imposed upon the grantee by this franchise, and to accept the same subject to all existing terms and conditions.