Fido

Was your ZTE Z222 purchased from Fido directly?  YES, brand new at the time... about 8 years ago. Can you also tell us the exact message you current see on your phone's screen? "No sim detected"Option to unlock or SOS shows up  Transferred SIM card o...

Same problem...out of nowhere the phone asks for a network unlock (16 digits) pin and does not recognize the SIM.  That phone was always with Fido.  Phone currently unusable.  Model  is a ZTE Z222 flip phone.