I manage a company in which we have 4 phones on our plan. 3 are available for upgrade mine is not because I just purchased the 16gb 3g two months ago. I would like to upgrade one of the other phones to the 3gs , but then switch that phone to my account while leaving them with a non iPhone. They are in maintenance and use durable flip phones , Is this possible. ATT is saying they have to tell me they cannot do it. How des the imei play into this and will I need a new sim card etc? Please help i don't want to wait two years for the 3gs.