Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
CallApp - Free Caller ID & Call Blocker app that allows mobile users to block phone calls, identify calls, blacklist unwanted callers and much more.
MessageBird - Reach 7 billion phones in seconds via SMS, Chat & Voice. Try it for free and improve your communication.
CallerSmart - CallerSmart is an application that is basically used for the purpose of looking up mystery phone numbers for free.
Plivo - Plivo simplifies your customer engagement.