Q: Factory Unlocked iPhone 4S can't be activated after reset to factory setting. "No SIM" message shows up. This phone is running on iOS7.1.

I bought this factory unlocked iPhone 4S 32GB from Apple store a few years back.  I've been using it in the United States (T-Mobile SIM), Singapore (M1 SIM), and Indonesia (Telkomsel SIM) with no problem.  Two nights ago I backed up this phone and reset it to the factory setting.  But yesterday when I tried to reactivate the iPhone, it keep asking me to "insert SIM card".  "No SIM" on the top left conner shows even I've inserted my T-Mobile SIM that has been used on that phone for months.  Has anyone had encountered the same issue or perhaps solution for this issue?  This iPhone is running the latest iOS7.1, Part No. MD244LL/A.