A little more detailed reading of that link reveals a lovely loophole.
Suppose we bought the Home 500 plan for 6 months that would be 500 x6 = 3000
6 months modem rental = 600
Security deposit = 500 (non-refundable)
Total cost per month = Rs.683 or Rs.766 if you add the modem installation charges.
Which is really quite bad when you consider Sify offers it at Rs.458 however there is a huge difference here because of this paragraph taken from the same page
As a special incentive to customers, to come forward and take up/ test the service, for both Home and
Business plans, additional usage charges (Rs/MB) for the use will not be levied up to 30th June, 2005 for the customers who join the service before 31st March, 2005.
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So you can actually download as much as you want for the first 6 months at a speed of 256kbps (32 kBps) with no limits!
If someone finds fault in my facts or calculations please tell me though I have thoroughly checked my calculations.