Can the public security system find the content of mobile phone short messages?

If the content of the short message involves a criminal case, especially an important clue of criminal case investigation, the public security organ at or above the county level may take technical investigation measures for the mobile phone number. This method can track the location of your mobile phone (it is useless to turn it off, but it can also be tracked), monitor your phone and intercept your short messages. Your phone calls and text messages (whether sent or received) will be stored on the computer of a company that provides communication services for a certain period of time (the exact time is not clear) before starting the technical investigation means. So it is not difficult to find out the contents of text messages and phone calls.