hi, i have the Samsung galaxy ace 2 but really don't like it and want to change to the Iphone 4s but I dont want to pay 75$++ a month. Would I be able to keep a plan of 30-40$ a month like i'm paying now? And can I get the Iphone using the medium tab? and how exactly does that work? Will I have to pay something upfront? I've asked around and keep getting different replies.