I don't think you need to do that nowadays. Yes, this was a thing that some people knew about in the past, and they used it to text for free or did other things like calling in other countries. I had also tried it when I was younger, but now I don't see the need to do that. You can easily reach people from all around the world for free using apps like messenger, Viber, or https://freetring.com/ . It is that easy, and you get better quality calls and fast messages.