i bought a brand new phone off amazon, the htc one for at&t to be exact. i transferred my number over from sprint to the new phone. turned sprint phone off, popped micro sim into the htc one from at&t and powered on. wasn't receiving any texts or anything so got curious. turned my sprint phone back on and i see everything is still going there, however when i make a call from my at&t phone the number that shows up is the one from my sprint phone. basically, i've got a sprint phone and an at&t phone both utilizing the same number, is this a case of after so long the sprint phone will be shut off or what? i'm selling the sprint phone to someone else but obviously don't want to do that if when they get it and turn it on the phone will be operating with my current number. just curious if this is a case where the sprint phone will be deactivated after a short period of time or what.