How does a SIM card work?
A SIM (Subscriber Identity Module) Card works by storing information about your phone service (e.g. your phone number) so that the phone it is inserted into knows what service and account to use.
You cannot call text or socially use your phone without one
no that would not work at all unless you are calling the police. the sim card contains memory that the company puts on it like what type of data you have. when you insert a sim card the phone checks to see its data. if you insert it nothing will happen exept it will say no sim card emergency calls only