iPhone compatible sim

hi all, my brother sent me iphone4 from canada to india,from last 8 months i was using it with turbo sim few days back i updated it to ios5.1.1 and after the update it says only compatible simcards from supported may be used to activate iphone now what solutions can i have for this problem . before unlocking is it necessary to insert compatibale sim then only unlocking is possible or else if i directly unlock it can i bypass the message saying compatible simcards ??