I just restored iOS 6.1.3 on my 4S, and tried to activate it with the SIM card of my iPhone 6S, so I could go back and forth between phones without an issue, but It wouldn't activate (it did finish initial setup, so everything else is working fine). iTunes returned an error saying, "The iPhone "iPhone" could not be activated because of an unknown error occurred (0xE00002D). Please try again later." The phone just says Searching... but if I plug in the old SIM, the signal bars show up, but it doesn't work anymore because the card is deactivated. Immediately I assume the newer SIM card (Nano with Micro-SIM adapter for the 4S) was too new to function with the older technology in the 4S, but I could be wrong. Any ideas?