It terms of their business policies, operators offer their clients “subsidised” offers when they purchase a mobile phone. In return, the client subscribes to a contract with a fixed term commitment (in general, either 12 or 24 months). With this practice, the client makes a contractual commitment to the operator in exchange for a lower price on their handset.
Your operator is required to inform you one month before the date of automatic renewal that the end of the 12 or 24 month contract period is coming to an end, and explain how to terminate the contract. At this time, your operator must advise you about the best price they offer for their services.
In the event of rightful cancellation before the end of the minimum contract duration, no charges may be applied to you, except for equipment provided which you conserve, but these costs may not exceed the lowest value between the pro-rata value agreed at the time that the contract was signed and the remaining share of the service costs running until the contract expires.
Beyond the minimum contract duration, you have the right to terminate your contract at any time, following a notice period of one month.