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.
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.