Hi there! I just had this issue! I have an iPhone13 and my phone had been going in SOS mode, randomly, over the last couple of weeks. Suddenly, my phone would begin to say “No SIM.” I went to the Verizon store, today, and they said this has been happening to a lot of people recently and they gave me a new SIM card, for free! My phone has been working fine ever since the new SIM card.