My friend lost his mobile phone and received "Please call the police if his mobile phone is lost!" What do you mean?

Your friend's mobile phone may have security software similar to the security housekeeper. This software can set anti-theft password and alarm information, that is, to write a message on the mobile phone in advance, you need to enter the phone number of a common contact. Once the mobile phone is stolen, as long as the thief pulls out the sim card and replaces it with another card, the security software will automatically send the written message (as you said) to the designated mobile phone number in the background of the mobile phone system. Notify the recipient that the mobile phone has been stolen. Usually, the number of the short message at this time is the mobile phone number that the thief is using, so that the mobile phone number of the thief can be locked, so as to finally find the thief. But remember not to scare him, but to outsmart him.