In the Settings section, make sure you select the correct telephone operator.

In order to avoid switching to a French operator, you should select whatever Swiss operator you are with.

Thank you very much for your tip! It will be very helpful in the furture when I travel to the border. I selected lycamobile, but was told service not available again... I have written to the customer service, but don't known when the problem can be solved.

if your service provider is limited to just lycamobile, you may find that you have no service outside of their zone. change the the provider in your settings on the phone to swisscom, orange or all. this way you will never be out of a service area. as roaming charges are now much lower, it shouldn't be a constraint.

Thank you so much! It just got back no normal itself somehow:)