Hi there , looking at various articles on the web brings me to the conclusion that it's still somewhat of a grey area. The fact is phone TV is still in it's infancy so i don't believe there's been any cases where the legitimacy of a license has had to be questioned. Anyway to try and answer your question i've taken this statement,
A valid licence entitles the licence holder and anyone who lives with them to watch live television on any device at that address and on any device powered solely by its internal batteries away from home."