I'm sure this has been asked before: I still have my old iphone 3gs that works great. However, I bought the new samsung focus (wp7) phone not too long ago, and I have been using that phone since I bought it. It came with a new sim card. I really like using the samsung focus, but lately I have been getting reminisicent. I want to use my old iphone again, for just a little while. I don't want to void any warranties, etc. But, can I just switch out the sim cards - or is this a big no no?
You should be able to switch the SIM cards with no problem. However, you will need to call AT&T to switch back to the iPhone data plan from the WP7 data plan, as the iPhone data plan has some differences in their systems that they will need to adjust for.