Because of a fierce competitions from carriers, telecommunications in France often means inexpensive plans with generous data and unlimited calling.
As an example, you can get unlimited-call and text plans with about 140GB of data for about EUR 25-40 (price range vary from carrier)
For your information, Orange France is the proprietor of all broadband lines in France.
Other providers rely on this network to provide you with the required service.
Most plans will require you to stick with the carrier for a definite amount of time as per mentioned in the contract. These are usually 1-year or more contracts.
There are however commitment-free plans available in all major carriers; whether that be from Sosh (Orange France brand) or Bouygues, Free, SFR and others.
Because of the duration of your mobility programme, you are encouraged to look for those commitment-free plans.
Terms to end your contract with a carrier will vary upon initial terms and conditions to which you agreed by signing the deal with the carrier.
It is recommended to be extra-careful while signing a deal so you know precisely the terms and conditions of the latter.
Please note: You may come across limited-time offers that are commitment-free, beware as it usually contains specific clauses that you should be aware of.