For some baffling reason, my mobile phone doesn’t show who’s calling. If somebody is trying to phone me, it just says "call" whilst ringing, offering no other information. If I missed the call, it just says I have a missed call from an unknown number. My phone is a Nokia 6600, but, bizarrely enough, the same thing happened on a new Nokia phone I bought. Could it be my SIM? Any answers (within reason and practicality) will be much appreciated.
Probably because it has fallen out with you.
Try being nice to it and remember to tell it you love it.