I think in India there are a lot of rural areas where people have extended family,
Indian people tend to be very family orientated even with grand parents, in comparison to much of the western world where we tend to do our own thing / escape from family

. We also see in the west, the emergence of new operators such as
Lyca mobile offering good rates for calling abroad.
It's very much the same here in China. Where's there's a very large migratory population, that might only see close family once or twice a year, they've usually travelled for work or education.
At my senior high-school, we have over 3,000 boarding students, many of whom are hundreds of kilometres from home. They only go home twice a year for Spring Festival and summer. Similar with many other schools in China. They all have cellphones with internet access. I think for them cellphones are pretty much a necessity to stay in touch with family and friends. The only alternative would be to write and send letters (snail mail). No students have their own laptops at the school, and school PCs with internet access are for academic use only.
Similarly with my friend from Badong, Hubei Province, whom I spent the Spring Festival with. Her large family, including grandparents live in Hubei Province, yet she lives and works in Wenzhou, Zhejiang Province, which is a long 24 hour train or bus journey away(flying is expensive in China, trains and buses are cheap but much slower). She only goes home twice a year. All members of her family have cellphones, again I think the only alternative way of communicating would be to write and send letters.
While cellphones are not an absolute necessity, they surely make these people's lives much better.
Myself, I'm certainly a long way from home. Thanks to things like Lyca, Skype Out, etc. it's very easy and cheap for friends in the UK to call me at any time. Certainly wouldn't be without a cellphone now.