Can you use an already activated straighttalk sim card in an iPhone 3GS?

I have a Nokia e71 right now and I was wondering if I can just use it's sim card in an iPhone 3GS

You can try and put the airtime card in it and see if it works. You need to go to the StraightTalksim.com website and update the data settings so that the phone will work correctly.

http://www.straighttalksim.com/support.php