A communication apparatus capable of receiving data designated to an identity number storing in a subscriber identity card, comprising: a radio transceiver module receiving a paging period parameter and a paging indicator parameter of the subscriber identity card from a wireless network, and receiving node-B signals comprising a plurality of paging indicators from the wireless network according to a first activation signal; a baseband processing module receiving baseband node-B signals comprising paging indicators from the radio transceiver module and processing the received base-band node-B signals according to a second activation signal; a controller coupled to the radio transceiver module, the subscriber identity card and the baseband processing module, obtaining a plurality of corresponding system frame numbers of a plurality of periodic radio frames according to the paging period parameter, obtaining a corresponding paging indicator position for the subscriber identity card in each periodic radio frame according to the paging indicator parameter, the identity number and the corresponding system frame number of each periodic radio frame, determining whether the corresponding paging indicator position is distributed posterior to a predetermined threshold position in each periodic radio frame, obtaining a first wake up time interval and a second wake up time interval distributed within each periodic radio frame according to the corresponding paging indicator position, generating the first activation signal to activate the radio transceiver module during the first wake up time interval, and generating the second activation signal to activate the baseband processing module during the second wake up time interval, wherein both a length of the first wake up time interval and a length of the second wake up time interval are smaller than a length of a periodic radio frame, characterized in that said controller is further configured to activate the radio transceiver module at the beginning of the corresponding paging indicator to receive a portion of the paging indicators during the first wake up time interval when the corresponding paging indicator position is not distributed posterior to the predetermined threshold position and configured to activate the radio transceiver module earlier than the beginning of the corresponding paging indicator to receive a portion of the paging indicators during the first wake up time interval when the corresponding paging indicator position is distributed posterior to the predetermined threshold position. a radio transceiver module receiving a paging period parameter and a paging indicator parameter of the subscriber identity card from a wireless network, and receiving node-B signals comprising a plurality of paging indicators from the wireless network according to a first activation signal; a baseband processing module receiving baseband node-B signals comprising paging indicators from the radio transceiver module and processing the received base-band node-B signals according to a second activation signal; a controller coupled to the radio transceiver module, the subscriber identity card and the baseband processing module, obtaining a plurality of corresponding system frame numbers of a plurality of periodic radio frames according to the paging period parameter, obtaining a corresponding paging indicator position for the subscriber identity card in each periodic radio frame according to the paging indicator parameter, the identity number and the corresponding system frame number of each periodic radio frame, determining whether the corresponding paging indicator position is distributed posterior to a predetermined threshold position in each periodic radio frame, obtaining a first wake up time interval and a second wake up time interval distributed within each periodic radio frame according to the corresponding paging indicator position, generating the first activation signal to activate the radio transceiver module during the first wake up time interval, and generating the second activation signal to activate the baseband processing module during the second wake up time interval, wherein both a length of the first wake up time interval and a length of the second wake up time interval are smaller than a length of a periodic radio frame, characterized in that said controller is further configured to activate the radio transceiver module at the beginning of the corresponding paging indicator to receive a portion of the paging indicators during the first wake up time interval when the corresponding paging indicator position is not distributed posterior to the predetermined threshold position and configured to activate the radio transceiver module earlier than the beginning of the corresponding paging indicator to receive a portion of the paging indicators during the first wake up time interval when the corresponding paging indicator position is distributed posterior to the predetermined threshold position.