BT unveils combined fixed and mobile phone service - but why?

British Telecom showcased world's first combined fixed and mobile phone system June 15, 2005 in London.

The system adopts only one phone and works like a mobile phone when the user makes or answers phone calls outdoors. As the user returns home it will automatically switch onto the fixed telephone line and the user will be charged at fixed line rate.

It will be tested on 400 homes before going nationwide.

Too be honest, I can not see how this would have mass appeal. Already is is being said that the blue tooth signal is not strong enough to switch the mobile to the fixed line in a large house. This would mean higher fees for the user.