Surprisingly, they don't overlap. Numbers are from the 2011 census. Interactive version at: https://bl.ocks.org/ganeshv/raw/fada13e56d2c5b7b1a78/
"In December 2011, over 300 million Indian citizens had no access to frequent electricity. Over one third of India's rural population lacked electricity, as did 6% of the urban population." (Wikipedia)
Checking 2011 article "The rural-urban distribution is 68.84 per cent and 31.16 per cent respectively" (The Hindu)
Multiplying those by 1/3 and 6%, that would make it 75% had electricity around 2011 and presumably a bit more now.
This works pretty well for Nokia 1100 style phones which had about a week or so of battery life which many people extend to a month by turning them off judiciously.