PhoneTray - Block an unlimited number of phone calls using USB voice/data/fax/caller-id dial-up modem.
Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Call Station - CallStation is computer answering machine, phone dialer, and Caller ID software.
CallApp - Free Caller ID & Call Blocker app that allows mobile users to block phone calls, identify calls, blacklist unwanted callers and much more.
SmartCallMonitor - SmartCallMonitor automatically matches caller data with existing Outlook contacts and displays them.
CallerSmart - CallerSmart is an application that is basically used for the purpose of looking up mystery phone numbers for free.