Why does the mobile phone receive a short message prompting that the sim card has been replaced? You can contact the sending number of this short message by phone. Why does my mobile phone show 66?

At this time, because one of your relatives, friends or acquaintances has turned on the anti-theft function, your mobile phone number is bound when setting this function. Because the SIM card has been changed or the mobile phone has been stolen, you will receive the message "The SIM card of the mobile phone has been changed, you can contact the sending number of this short message by phone to help you find the mobile phone". When you call someone, it's not your name, but the number 6603. This is because the other party is in the same cluster network as you, and the eighth and ninth digits of your mobile phone number are 03.