I have an unlocked iPhone. (but still using AT&T) I also have a Samsung slider. I'd like to be able to use both with the same number. In other words, I'd like to be able to copy my sim card and put the copy in my slider so I can use whichever I prefer whenever I want without having to take the battery out all of the time. Is this possible? I've seen something called "GSM 6 in 1" that claims to do this, and you can even have both phones turned on at the same time (but only one can be in call at a time). That thing is $60 though. Is there any other way? And is it possible to do it with a sim card that was already attached to an old phone number? Meaning can I overwrite the info on an old sim card? Thanks for any advice!