From True Software Scandinavia:
Truecaller lets you search beyond your phonebook, identify unknown incoming calls, block calls you don't want to receive, and make relevant contact suggestions based on time and place - so you never have to leave the service to find the right contact. See who is calling if you don't have their number in your phonebook. Block unwanted calls from spam callers and telemarketers. Search for any number in the world to see who it belongs to. You can now copy a number anywhere (e.g. website or apps) and Truecaller will notify you who it belongs to. Get in touch with people via name search (Premium feature). Tweet and Follow a person on Twitter directly from Truecaller. Yelp! integration for faster business search results.
Truecaller never uploads your phonebook to make it searchable or public. 3G or WIFI is required for Truecaller Caller ID to work. Operator charges may apply. The block text feature is currently not supported for devices with Android 4.4 (KitKat).
What's new in this version:
We have fixed the issues on Android M devices reported by some users.