What carrier is this phone locked to and what sim card are you inserting? You can buy an unlock code on ebay http://shop.ebay.com/i.html?_nkw=blackberry+8100+unlock+code&_sacat=0&_dmpt=PDA_Accessories&_odkw=Samsung+SGH-A877+digitizer&_osacat=0&_trksid=p3286.c0.m270.l1313
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What carrier is this phone locked to and what sim card are you inserting? You can buy an unlock code on ebay
http://shop.ebay.com/i.html?_nkw=blackberry+8100+unlock+code&_sacat=0&_dmpt=PDA_Accessories&_odkw=Samsung+SGH-A877+digitizer&_osacat=0&_trksid=p3286.c0.m270.l1313