Even better they partnered with WhatsApp and offer "unlimited WhatsApp" packs:

http://telecomtalk.info/tata-docomo-launches-unlimited-whats...

SMS costs Rs1 per

The number of WhatsApp users in India is still infinitely less than the plain vanilla SMS people. Specially the ones living in villages which is a huge majority with a huger margin.

We also have SMS packs like 100 SMS a month by paying Rs 40 or so. But a DoT rule (which was actually twisted and misinterpreted by telecos) make that plan ineffective on any festive day and on those days you pay for each SMS and the rate is almost double or x3 or sometime x4 of what you would have paid without the SMS pack :-)

They did for prices ranging from $1 - $2 per month. But text messaging does not do groups remotely as well as Whatsapp does.

Indian telecom sector is highly regulated by the Govt. And it is very competitive. So there's no way such an all-or-nothing deal can be introduced so late in the game.

Edit: Moreover, the telecoms do make money on the data plans don't they?