my new replacement thunderbolt arrives tomorrow (had to exchange it due to several problems with the first 1)... my question is do I keep the old sim card and use it in the new phone or do I use the new sim card that will come with the new phone? The Verizon guy told me when making the call to get a replacement that everything would be new including the sim card...but I thought once you had a sim card, it stayed with you from phone to phone???