The Blankfont or Blankfont.A trojan runs on the Nokia SymbOS.
This trojan is spread via Bluetooth. It pretends to be a game called Troop 3. Once downloaded, it is present in memory. When the user restarts the mobile phone, Blankfont corrupts the font pack leaving no font on your phone. Meaning that either scrambled random symbols will appear, or no text or symbol at all.
The virus has two variants, Blankfont.B and Blankfont.C, but they are unchanged from the A variant.