I just upgraded to a 3GS 16GB for $199 using my wife's phone line which was eligible for upgrade. I currently have a 3G on my line which wasn't upgradeable. I plan to get the new 3GS and replace my 3G. I don't think the 3GS will be on my wifes number unless I activate the 3GS on her SIM when I get the phone. I will try to activate the new 3GS using my current 3G SIM. I will have to make sure they keep my wife's existing phone activated on her line. Does this make sense or does anyone see any issues with this? Is there any word that the 3GS will need a new type of SIM for the faster data?