A mobile communications device with a wireless module and a controller module is provided. The wireless module performs wireless transmissions and receptions to and from a first service network and a second service network. The first service network and the second service network are in compliance with a first communication protocol and a second communication protocol, respectively. The controller module performs measurements on the first service network via the wireless module, and generates a measurement log according to the measurements results. Also, the controller module receives a handover request from the second service network via the wireless module for handing over from the second service network to the first service network, and transmits a handover response indicating availability of the measurement log to the first service network via the wireless module.