Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
CallApp - Free Caller ID & Call Blocker app that allows mobile users to block phone calls, identify calls, blacklist unwanted callers and much more.
CallerSmart - CallerSmart is an application that is basically used for the purpose of looking up mystery phone numbers for free.
Sync.ME - Search over 1 Billion phone numbers worldwide. Identify unknown phone numbers and block unwanted calls.
Number Guru - Number Guru is an application for smartphone users for the purpose of reverse phone and caller lookup system.
Should I Answer? - See what phone numbers are most searched and find ratings and users reviews.