This time...
I bet BT marketing will mess it up yet again. Ten years ago there was the "One Phone" which was actually 2 phones, and they wanted a ridiculous amount of money for it so they hardly sold any. Intermediate incarnations were full of the sort of turn-off "features" that only fans of DRM could like. I have a fusion hub and its locked to BT so I can no longer use it, and neither can BT! (Anyone know how to unlock it?). The only good thing about such things is that the miniscule take up helps reduce the landfill produced by it. Our so called competition authorities should pull it out and do something to encourage this kind of service to be implemented such that you can choose your mobile phone service supplier independently of your broadband supplier, but I'll not hold my breath while the chocolate teapot melts.