Using Postman's phone to talk to Son

When I was young, my family would wait for postman to come and deliver mail to us. Now, postman comes with phone and a mom in Bihar can talk to his paddy laborer son in Punjab using postman's paid wireless local loop phone.
In this age, when time is the most precious thing, writing letters will decline, even in rural India. So, using postmen to take the phone to most poor areas of India is a good deed as well as new revenue stream.