I currently have an iPhone 5s from Virgin. I really want a 6+, but virgin and boost don't have. I like paying $43.67 each month without all the hidden extras that come with the big carriers. Sprint net work would be nice because it is the only service in my work area. Is there any way I can use my current SIM card in a 6+ and keep virgin? Or Boost? I tried reading thru the other thread and got confused. Thanks for any help.