Can you use a straight talk SIM card from a iPhone 4S on a Samsung galaxy s3?

I have a factory unlocked iPhone 4S right now with a straight talk SIM card in it. I am wanting to get a Samsung galaxy s3 and use it on straight talk but I was wondering if I have to buy a new SIM card or can I just use the one that I have been using on my iPhone 4S. And also I am wanting to do a straight trade for the phone so I was wondering is there anyway I can keep my same number if I won't have both of the phones to transfer the number?

Just put the sim card in the new S3 and it will transfer the phone number. Won't leave the number on the iPhone. If the S3 is the MicroSim version you may have to get a sim converter. With sim cards, the phone number is stored on them, so you'd be able to keep your same number. What you do need to make sure of though is that the S3 you are buying has all bands set up for Straight talk. Otherwise you may end up with a phone that can only go on the Web with edge (if at all) and no picture messaging. Make sure it is set up to be provisioned to straight talk, or certain features won't work.