hi guys, i got my own n80 since june 07...the only problem is screen & speaker (change the ribbon only). But yesterday i subscribe with celcom postpaid(changing from prepadi to postpaid) and until today i still cannot use my line  . The error message on my phone is "SIM Card Not Valid". My sim card can be used on other phone and other sim card can be used on my phone (tested after i found that error). I called celcom careline to ask what's the problem and they said i have to check with nokia. So anyone here can help me or give me some suggestion?