We have upgraded our iPhones and have an unused iPhone 3GS. It is no longer hooked up to either the phone network or a data plan. We would like to simply use it as an iPod. Is this possible? We recharged the battery, but it wants us to update our iTunes. It won't do that. I checked and there is no SIM card. I assume that the store removed it when we switched phones. Is it necessary? Can it be replaced? Thanks.
The SIM should not be necessary since the old iPhone was already activated.
When I upgraded to my iPhone 4, the AT&T store did the change over and activated the new phone and SIM card, and deactivated the old SIM. When I got home, I pulled the SIM out anyway, and have been using my old 3Gs as an iPod touch every since. You can still sync it and everything just fine, since it will already be activated in iTunes - all I did do was rename it in iTunes. I even went ahead and updated it to iOS 4.3.
While you don't need a sim card in an iPhone to use it as an "iPod", a sim card MUST be installed in the phone to upgrade software or restore the phone, should the need arise. The sim card need not be activated, but it must be present. I always advise to leave the deactivated sim in the phone for this very reason.
I have installed new apps, updated old apps, update the iOS, backed up and sync'd - all with no SIM card in my old 3Gs. The SIM card should only be needed if the device was not already activated in iTunes. As long as it was, the SIM is not needed to fully use the device as an iPod touch. A restore, yes, would require the SIM to be present if you wanted to do a clean setup or restore from backup.
I've seen it. I don't really care what it says, I know that I have actually done all the things I said without a SIM card in the device. In my experience, it has not been necessary at all to continue using my 3Gs as an iPod touch device. My update from 4.2 to 4.3 went just fine without it, and since then I have also added some new apps and sync'd at least twice, all without a SIM card.
It might be necessary under some circumstances, but certianly not all.