This question has been posed in various forms, I know, but I haven't been able to find a straight answer (that I can understand): After upgrading to the iphone 4s, I want to use my old 3Gs as a dedicated iPod. I've activated it, and renamed it via iTunes with the old SIM in it. I've since removed the SIM and all is good. In fact, this morning I connected it to the iMac and upgraded the software to 5.0.1 without the SIM. My question is, is there any reason to have removed the SIM in the old phone, or should it be left in place? (i.e. will I screw anything up by using it without the SIM). Or does it make no difference? Apologies if this has been answered here before and I just missed it.