Cell phones during working hours

I can't speak for the labor laws of other countries, only the US.

An employer can set any REASONABLE rules that affect the efficiency of an employee. An employer has to make available a means for an employee to receive communications of an emergency nature (i.e. sick child, house on fire, death in family, etc.). However that means is of the employer's choosing (i.e. he can provide a emergency number for family members to call). If employee use of cell phones affects their efficiency, the employer is perfectly within his right to ban their use during working hours. If the use of cell phones affects other employees efficiency, the employer has the right to ban the use of cell phones in specific areas, or entire buildings. An employeehas no more right to the use of a cell phone than he does to play video games or watch Soaps during work hours. If your work situation is such that you spend many hours with NO means of being contacted in case of emergency, then you may have a grievance. Otherwise, you don't.

Probably not the answer you want to hear, but that's the way it is.

Health and Safety directives would also come into play here.

One should not use a cellphone when it is not safe to do so... driving, working with explosives, where interference causes issues etc.

The obvious solution is for the employer to invest in a Faraday cage or jammer though :-)