Overview of Some Voice Over IP Calls and SMS Verifications Services Providers

This book provides brief survey of the some Voice Over IP (VOIP) providers, including the providers that offers free calls to some countries. Then, I will mention some websites that offer virtual phone numbers from around the world to receive activation codes and SMS confirmations online..The report consists from the following parts:1. How does VOIP work?2. Getting free phone number in US or Canad...