Some iPhone 4S owners have been experiencing a peculiar situation where the device stops recognizing their SIM cards. Users have been reporting that they receive error messages on the iPhone 4S stating that they either have no SIM card installed or their SIM is invalid. Rebooting the handset works as a temporary solution, but most users experiencing this problem have reported that eventually the iPhone 4S will refuse to recognize the SIM at all.
This issue doesn't appear to be isolated to any on
