Okay, this just happened yesterday. In the middle of the day, my phone suddenly dropped the data signal, and when I tried to call someone, it kept saying 'not registered on network'. I just recently paid my bill, and when I called my network provider, it told me that my sim was fine; my number wasn't blocked, data, calls and texts aren't barred either. So I researched online, saw how to look up the IMEI number, and this is the number it's giving me: 004999010640000/01 It is a different one from the IMEI number on the back of my phone battery, and according to the internet, it is a fake/invalid one. I would appreciate some help and advice! Thank you!