How should you inform the operator you leave?

If you want to keep your number the operator whom you will go to will inform the operator you leave. You have to sign a "letter of authorisation" showing that you want to keep your number. With this letter your new operator can take the necessary steps (of a technical, administrative, or other nature) with your previous operator.

Attention: leaving an operator providing his services through an access code (CS or CPS operators) does not impact the call number, which stays where it is, but some of these operators require you to inform them in writing of the fact that you no longer want to make use of their services. Please do so as soon as you have subscribed to the services of your new operator.

If you do not wish to keep your number, it is up to you to cancel the contract in writing with the operator you leave. You can cancel by means of a letter or an e-mail, SMS or on the website, if your operator has a system to receive this kind of "message").