I am using truecaller app since last year and found very useful app. It provide you details and name of unknown caller while they call you. However it had also limit that it can't show details of every number but still show maximum. It used crowd sourcing feature to show the number details. It has own dialer and messaging feature and also provide call recording feature if you pay for it. I like she camera search feature. When any number show in front of camera it automatically show the details of any number. If you pay for it they provide you request option so you can request number in private. Anyway it deserves 3 out of 5 star according to me. Thank You