The iPhone has a reputation as being very secure, so much so that the FBI has had publicized problems getting into them in various investigations in recent years. Most people are fairly confident that the average would-be thief is not going to be able to get past their Touch ID or Face ID, or guess their security code. Even if they can, the owner can use Find My iPhone to figure out the phone's location, and to erase it if it contains highly sensitive data. But how many iPhone owners have considered that a thief could take and use their SIM card to make calls and use data?