Been searching the net and forums and not found anything to match this situation yet. I have a iphone 3g that I own which I recently swung over to corporate billing (my company is picking up the bill). Unfortunately they (my company) are not allowing me to upgrade the hardware due to their policy that you must have your account as corporate for 2 years before you can do so. (again this is my company not AT&T) My question is if I buy an iphone 4g outright and then cut my existing activated sim from my 3g, will that work in the 4g? Hope that makes sense.... my only other option is to have my company drop me and pick up my own tab but if cutting my current sim for the new 4g will work then even at the full price cost of the phone I'll save money in the long run. If anyone has any experience with this, please respond. Thanks!