If you're a BT customer whether residential or business they will have sent you a username and password that will let you access BTWiFi and FON hotspots when mobile. The username will be a @btconnect.com or @btinternet.com email address. Your phone or tablet or whatever will find the hotspot and connect to it. When you connect to the internet it will open a BT Wifi login page to enter these details.
You don't need any special equipment to do this.
The FON box is only needed if you aren't a BT broadband customer.
Goodness this sound too easy I have a username & password for BT openzone but assume this ios not the same thing. Don't recall having another username but will be looking into it when we get home on Monday..............:thumb: