Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.

Callblock - The first app to block telemarketers automatically in iOS

WhosCall - WhosCall is a reliable caller ID app whose popularity has led to its adoption by many users including international media. You can now manage the numbers calling you regardless of whether they are part of your contact list or not... read more.

CallApp - Free Caller ID & Call Blocker app that allows mobile users to block phone calls, identify calls, blacklist unwanted callers and much more.

Hiya - Know who's calling or texting and block spammers on Android

Should I Answer? - See what phone numbers are most searched and find ratings and users reviews.