I ordered my new 3GS under my wifes line on our family plan. I have a 3G, she doesn't have an Iphone. This morning when I got my 3GS I called ATT and told them I wanted to put the IMEI of the new 3GS on my line with the old 3G. Afterwards I activated the 3GS and it told me to wait possibly up to 2 days to activate due to the overload of activations. I have been waiting all day for it to activate. After reading on this forum this afternoon I tried to swap my old 3G SIM with the new 3GS SIM and it immediately activated.