A mobile communication device is provided with a wireless module and a controller module. The wireless module performs wireless transceiving to and from a service network. The controller module receives, on a paging channel, a first predetermined number of symbols in a frame of a time slot via the wireless module, and determines whether to enter a standby mode according to the first predetermined number of symbols. Also, the controller module stops the receiving of subsequent symbols in the frame by deactivating the wireless module in response to entering the standby mode.