A friend's family is heading over to travel in Switzerland and Germany for a few weeks, and they'd like to rent cell phones. 2 adults and 2 teenage kids are going; they'll probably want to have 2 or 3 phones, and they'd be using the phones both to contact each other during the day and to call people elsewhere in CH and DE.

They'll be arriving in Zurich. What are the better options that they'll have for renting phones, either at ZRH or a reasonably convenient location in the city?