Methods for monitoring paging messages with reduced power consumption and communications apparatuses utilizing the same

A method for monitoring paging messages in a mobile station with a subscriber identity card camping on a cell, comprising:

• monitoring a paging channel from the cell at a special position of every predetermined time interval subsequent to the last monitored time;
• detecting whether a same first identity information is repeatedly broadcasted in the paging channel at special positions of different predetermined time interval;
• determining the total number of periodically repeated paging messages containing the same first identity information;
• determining a new time interval by multiplying a time period between two successive repeated paging messages with the total number of periodically repeated paging messages, wherein the new time interval comprises a monitoring interval equaling to the length of the time period and a sleep interval, and the monitoring interval comprises a plurality of predetermined time intervals;
• monitoring the paging channel at special positions of the plurality of predetermined time intervals in every new time interval subsequent to the last monitored time so as to receive subsequent paging messages from the cell.