I'm from the US. I had Verizon unlock my phone so that I could put in an international SIM card when I traveled abroad. However, when I put in the international SIM card, I lost the original Verizon one that was inside. Do I need this original SIM card when I go back to the US? Wil my 4S work without it? I also plan on getting my phone replaced with AppleCare-- will a new SIM card come with it?