Sorry for this basic question, but this is the first phone I've ever owned with a SIM slot. I called Verizon this morning and got my phone unlocked for international use. I popped open the SIM tray and noticed there is already a verizon SIM card in there, presumably for their own global roaming plan. Is there any disadvantage of just taking this card out and leaving it out? I plan on using a local SIM card whenever I travel overseas so I don't have to pay Verizon's ridiculous international rates. Will the phone function properly without this card in the slot?