It can be worse than you imagine. Your cellphone will get stolen. Remember, that you will not be able to buy a replacement phone and card because your ID was stolen as well and will be cut off for weeks. The cellphone companies will take ages to process your report (especially since you won't have an ID) since they make money as long as the phone is active. Copying the banks, let's say it will take two working days (i.e. about a week) to process your request.
In the meantime, your phone and SIM will be used during a crime. The police will trace the owner - not because they are so clever, but because it will be one of the easiest things to do. Your cellphone company will provide your details to them and they will arrest you (unless you live in an informal settlement - and I suggest that everyone forced to register, claim to live in a shack). Now you will be in jail, not even a SIM card up your @ss and will have to prove your innocence. Good luck.