Google Accounts settings page has a new feature called “SMS for Hangouts”. You can “add your phone number to receive messages from Google+ Hangouts as SMS, when you are idle.” Google goes on to explain that “SMS is less secure and may be less reliable than web-based communication. All messages sent by SMS are sent via your mobile carrier network, without encryption.”
This features works for most of the countries where Gmail SMS is supported, but not the US. It works for India, Pakistan, Israel, Turkey, Ukraine, Congo and many other countries from Africa and Asia.
{ Thanks, Herin and Camilo. }