If you took your phone from the operator, you will only be able to use it with a SIM card from this operator. To be able to use it with another operator like
SFR or Bouygues Télécom, you must make a request for unlocking to unlock your mobile phone for free. This request is free and fast.
To proceed to the free unlocking of your mobile, you must have been the owner for more than 3 months. If you bought it less than 3 months ago, you will have to pay 76 € from your operator to unlock.