There is provided a method of operating a femtocell base station comprising, following a hand-in or reselection of the femtocell base station by a mobile device, determining a reason for the hand-in or reselection by the mobile device and adjusting a maximum permitted transmission power of the femtocell base station according to the determined reason. A femtocell base station for use in a communication network is also provided that comprises a processor configured to perform the above method following hand-in or reselection of the femtocell base station.