Some airlines (e.g. Lufthansa) also install GSM microcells in their planes. They allow you to completely disable flight mode, once you're at cruising altitude

Some airlines (e.g. Lufthansa) also install GSM microcells in their planes. They allow you to completely disable flight mode, once you're at cruising altitude -- and therefore out of range of the terrestrial cell network. (Whether your cell provider will actually allow your phone to associate with the in-flight microcell is a different issue...)