The ARTCI makes calculation of the cost, taking into account: - the costs directly chargeable to the services concerned; - the common cost in proportion to their contribution to these services; - costs integrating the cost of the capital invested. Article 174 : The operators and services providers are compelled to inform the public of the tariffs and the general terms of their services offer. They communicate this information to the ARTCI one month before informing the public. The tariffs applied by the powerful operators and service providers must be directed towards the costs. The service provided by the operators and service providers is open to all compliance with the general requirements of the offer specifications is not spoiled. The operators and service providers set up systems of measurement guaranteeing the effective application of the tariffs published. The ARTCI periodically checks the effective application of this principle and penalties for the offenses observed. Article 175 : The contracts entered into between the operators and service providers and the users must specify the conditions of the supply of service, its technical characteristics, the attractiveness of the in the event of undergone damages. The contracts must be entirely written in French, in the same police and be clearly legible. It must specify: the various types of service with a view to national and international telephony the reception is considered as separate services; - general requirements of the offer, service and types of maintenance service offered; - the decomposition of the tariffs of the services provided prices and variable prices; - conditions of interruption of the service in the event of unpaid invoice; - compensation and appeal procedures available to the user in the event of undergone damage; - compensations provided in the event of a breach