What is BT Openzone and what can it be used for?

BT Openzone is a popular WiFi hotspot in UK, provided by the BT Group. A WiFi hotspot is an open-sourced wireless internet connection for any mobile device, such as a smartphone, laptop or game console. BT's network currently occupies 40% of the UK's WiFi hotspot market and can be found in local cafes, pubs, hotels and airports. Access can be obtained by purchasing a "pre-paid voucher" either on site or through BT's website.