This has the potential to be a game changer. While this article does not speak whether they plan to use internet / data here, I believe the real potential will be tapped if the program is run irrespective of data availability. Despite impressive mobile network reach, countries like India have some time before data is pervasively available.
So there is nothing to boast about here, yet let me point to one of my posts from few years ago where I had discussed on the missed-call innovation. You can read it here - The very interesting "Missed Call".
I had described a few use cases there. The whole concept of missed call is on the basis of what I called "inter personal communication protocol (IPCP)". That is the knowledge of what is to be done is known only to the 2 parties exchanging the missed call - The idea of IPCP is the users decide the meaning of the missed call.
Facebook (and I am sure others will follow soon) are tapping this IPCP with some enhancements. Lets see where this innovation goes.