That is correct. Any cell phone sold in the United States by law is supposed to be able to dial 911 no matter whether they have a SIM card inserted or not and no matter whether they have service on a SIM card or not and also no matter whether one specific carrier in your area has no signal it will use the others instead. You may be a Verizon customer, but if you dial 911 and an AT&T tower picks up the call first, the AT&T network will serve that call instead.
That is correct. Any cell phone sold in the United States by law is supposed to be able to dial 911 no matter whether they have a SIM card inserted or not and no matter whether they have service on a SIM card or not and also no matter whether one specific carrier in your area has no signal it will use the others instead. You may be a Verizon customer, but if you dial 911 and an AT&T tower picks up the call first, the AT&T network will serve that call instead.