i have an extremely crappy nextel i265. i hate it. its sim based and since i have to stay with my current sprint/nextel plan am i able to put the sim card into any unlocked phone and use it with my same service? how does this work? if i could change service providers entirely id love that but i cant so im looking to get at least a nicer phone. i really want a slide phone, cuz its fun to slide. x] possibly with qwerty for texting. (sms i believe?) so yeah. ima n00b i know it. help please.