Guys thank you for your help. I finally found out what was the problem. DSL 502T is actually a router with in-built dialer and you just need to switch it on and no need to dial from your computer as you would do for a modem.I found it by accident. Mean time I had posted my Router for sale in eBay and even took the application form from BSNL to get a new modem from them. Luckly i found the solution before any one could actually place a bid for my router in eBay :lol: