The last discussion of this topic I found was a few years ago.
My wife will be in Europe (Germany, Italy, France) for business for 3 weeks. Because of work she will need calling service. She will be spending the first night of the trip in Frankfurt and she would like to buy a SIM card at the airport. Does anyone have a recommendation based on experience? She knows she will have to give a German address and proof of identity.
Thank you in advance,