These microcells are small devices, about the size of a DSL or cable modem, that create a local cellular service zone up to about 40 feet from the device in which you can make and place cell phone calls and, if you have a smartphone, use data services to access the Internet.
As long as BT controls the "local loop", the last link from the network to a phone or modem, and insists on metered access, it hardly pays to offer unmetered web deals.