There is a country in Africa that's been using something very similar for some time now.
Let me look it up and I'll edit this post with a link!
Followed!
Don't forget to take a look at my blog ;)
Edit:
It's called M-pesa and it's very popular in Kenya specifically.
Here's a link I found https://www.cnbc.com/2013/11/11/cashless-africa-kenyas-smash-success-with-mobile-money.html
But you can of course Google M-pesa for more info.
Cheers!
mPesa - Kenya