If the device gets lost or stolen, it is important that you report the matter to your carrier and the police and they are likely to ask for details like the device’s IMEI number, IMSI, SIM number, etc. It helps if you can keep a record of this information somewhere outside your phone. You can find the IMEI number by dialing *#06# or get the SIM reader app and it will instantly extract the SIM and Device info that you can save to your email account.