Start with a free online imenik (imenik.hr or mojbroj.hr). If that fails, call 1144. Do not expect mobile numbers to appear.
It seems you're asking for a review of the “most accurate phone directory by name” — likely referring to services like , or other Croatian or regional directory assistance services (since “najtočniji telefonski imenik po imenu” is Croatian). najtočniji telefonski imenik po imenu