While the world's No.3 phone maker, Apple, is expected to be fighting to hold onto its customers with the launch of new iPhones this week, the world's No.1 and two phone makers have been fighting over something much bigger: the very future of the phone.

At the IFA technology show here in Berlin, both Samsung and Huawei were showing off their huge folding phones, the Galaxy Fold and the Mate X, respectively, and asking a very simple question.