Why can iPhone receive SMS without sim card?

It is said that 4s has many secrets. Foreign mobile phones have penetrated into our lives, and information design can be accepted without cards. The idea is this. When there is a major event or war in our country, ZF will definitely cut off the server connecting communication equipment with international standards, and then we can only receive official one-sided news. Apple can still receive international news through international satellites (mainly American satellites) without a SIM card, and it can send information to us at any time. So .............. is very strange. . . .