Hello I'm a long time sprint customer (10 years) and I've stayed with them b/c of their economical prices. Lately, i've been unsatisfied with their customer service and dropped calls. I'm considering switching but I need to wait until early next year to make this decision. I want to own an iPhone 6 but would like it to be domestically unlocked which I know sprint does not do. If I buy a tmobile iPhone 6 that is unlocked can I use all aspects of the phone (voice, text, data, VM) if I put in my current Sprint sim card? Alternatively, if I buy a Sprint iPhone 6 and pay it off, will I be able to place another devices's simcard early next year when Sprint domestically unlocks their phones? Thanks for any help!