4. Interconnection shall not be subject to unjustified interruptions or unavailability of services. 5. Any dispute relating to interconnection shall be submitted to the regulatory entity for arbitration, without prejudice to recourse to ordinary jurisdiction. CHAPTER III Common provisions Section 15 Obligations of operators and providers of telecommunications services Operators and providers of public telecommunications services shall furnish adequate and updated information on the terms and conditions for providing services that are part of the contracts to be entered into with clients, under the terms established by the regulations to be approved as a follow-up to the present Decree-Law. Section 16 Rates The rates of telecommunications services provided on a competitive basis are fixed by the respective providers, and the various components thereof shall be announced and disclosed to the general public, in a detailed, clear and unequivocal fashion, under the terms to be defined in the respective operating regulations. Section 17 Terminal equipment 1. The acquisition, installation and preservation of duly approved equipment shall not be subject to any rules, and its connection to the public telecommunications networks shall be in compliance with the conditions established by law, with a view to safeguarding the wholeness of those telecommunications networks and adequate interoperability of services. 2. Manufacturers, importers, vendors or other occasional holders of terminal equipment designed to be connected to the public telecommunications network shall apply for its endorsement with the regulatory entity, with a view to safeguarding the smooth functioning of the network. 3. The provision of installation and maintenance services for terminal equipment of clients of the public telecommunications network may only be conducted by natural or corporate persons with the required technical qualification and duly authorised by the regulatory entity.