The employer has the possibility to restrict the rights of employees and their individual freedoms. But that does not mean that it is possible to completely ban the use of personal phones during working hours.
No, a general and absolute ban on the use of the personal phone would be very risky.
Restrictions must be justified by the nature of the task to be performed and proportionate to the aim pursued (Labor Code, art L. 1121-1).
The rules of procedure can not also include restrictions that would not be justified by the nature of the task to be performed and proportionate to the aim pursued (Labor Code, Article L. 1321-3).
However, for safety reasons, you can prohibit the use of telephones, for example when driving equipment, handling dangerous products, in case of risk of disturbances of electronic devices, etc. But prohibiting an employee who works alone in an office to use his mobile phone does not seem justified.
The use of the cell phone jammer can cause nuisances for other employees. It must therefore be used discreetly. Rules of use can be put in place such as asking employees to put their phone on vibrator mode, make phone calls outside the office if the latter is shared with several colleagues, for example.
The Commission Nationale Informatique et Libertés (CNIL) admits the use of telephone and Internet for personal purposes within the company, provided that it is a reasonable use.
It should not be forgotten that the employee executes his employment contract in good faith. The use of the phone must be reasoned. It must not be at the expense of its work performance. In case of abuse, the employee could be penalized. It is still necessary to be able to prove the abusive use of the personal telephone during working hours …
In order to determine precisely the extent of your rights in disciplinary matters, Tissot Editions advise you their documentation “Tissot social entreprise” where a complete file is devoted to “Discipline and disciplinary procedure”.