There are set-top boxes, from ISPs that are also mobile operators, which embed femtocells. When a mobile subscriber is using such a femtocell, it doesn't count towards the mobile data cap.
Imagine the convenience of having a wireless network in your own home!
Although of limited range, the femtocell is public, not limited to the landline customer's use. This handily covers shadowed areas in cities as well as remote areas, reduces load on main cells, and Tx power needed both ways.