Suppose I dont have any landline nor any broadband connection and I opt for BSNL BBG FN 500 COMBO plan, then how much will I have to pay in total.

This is what I've understood:

Rs 500 for modem security + Rs250 for modem installation + Rs 250 for landline connection = Rs 1000.

Now let's assume I apply today and get the connection on 1st of december, and my total chargeable download for the month of december is less than 1.5GB. Then the bill comes in january 2012, and I pay Rs 500 + Rs 50 for the modem i took on rent. Right? So First I need to pay Rs 1000 when applying and then Rs 550 in january. Am I correct? I will be really thankful for a yes or no answer and will deeply appreciate any explanations if I'm wrong.

PS: Please don't assume any scenarios other than what I mentioned. Thank you in advance to whoever answer me.