An Iphone, and I believe it is a legal requirement for all phones, even without a SIM card, can call the emergency line without a SIM card that would give it a number to call and call to.
Anyway, a while ago I remembered a tv commercial from the government about the emergency number. Among other things it said that they record your number so that they can call you back if something goes wrong like your call gets cut off or something. So, can they call you back even if you dont have a SIM card? Since you can call yourself from a phone without SIM card.
This stuff about the emergency line might not apply to the country that you live in, but the question remains.