Section 4: Persons authorized to set up a network open to the public and providers of telecommunications services, as well as members of their personnel shall be bound to keep secret the content of users' messages. Section 5: (1) Actions and practices which aim to, or may-prevent, restrict or compromise competition in the telecommunications market shall be prohibited, especially when they tend to: - limit access to the market or free competition from other enterprises; - obstruct price fixing through the free intervention of market forces by artificially hiking or lowering them; - limit or control production investments or technological progress; - cut off markets or supply sources or create regional monopolies. (2) An enterprise or group of enterprises shall also be prohibited from making abusive use of: - a dominant position on the local market or a good portion thereof; - a situation where a client or supplier without an equivalent solution is economically dependent on him. Such abuses may consist, in particular, of unjustified discriminatory refusal of access to telecommunications networks open to the public or to the supply of telecommunications services, as well as unjustified or discriminatory discontinuance of established commercial relations. (3) The following practices shall not be subject to the provisions of 5(1) and (2) above; - practices resulting from the implementation of a legislative or statutory instrument: - practices which the authors can prove are intended to ensure economic advancement and whose users are allocated a fair share of the profits accruing therefrom, provided that the said practices do not entail elimination of competition for a substantial portion of the products and services concerned. Section 6: Any undertaking, agreement or contractual provision relating to a practice prohibited under section 5 above shall be null and void. PART II LEGAL REGIME OF TELECOMMUNICATIONS NETWORKS AND SERVICES Section 7: Telecommunications networks and services shall be governed by one of the following regimes: - concession; - authorization; - declaration. CHAPTER I CONCESSION Section 8: The following shall fall under the exclusive rights of the State: