TrueCaller is a Symbian S60 3rd and 5th edition based application to let you see who is calling. TrueCaller shows you who the caller is on incoming calls if the number is not stored in your phonebook. After the call you can easily save the caller info to your phonebook or view it on a map.
The data is being updated daily which means that if you don't get a match on a number today, you might get it tomorrow. 3G or WiFi connection is required for lookup during incoming calls. You can read more about this application from truecaller.com. The application works with Nokia X6, 5800 XpressMusic, 5530 XpressMusic, N97, N97 Mini and 5230.