Here is a little guide to configure NetGear ADSL DG834G router with BSNL broadband internet connection. I have done it and also setup a Wireless AP at home to hook my new HP Pavilion Laptop. 
Follow Me!
A Cultured Clown's perceptions – ஒரு நாகரீக கோமாளியின் பார்வைகள்
I think its better to leave the authentication part to the modem rather than router.
1.In case you router goes wrong, u can always plug in the cable from modem (saves a lot on ur configuration time)
2. You would make use of both Modem & Router firewall when configuring with the above method.Twice secure.
NetGear ADSL DG834G router is a modem +router
this is not applicable for you 
Yes Man. Absoultely right. But anyway, the one you mentioned will be helpful for people with separate devices for ADSL Modem and Wireless routers.
The settings are not working for my netgear router+modem for BSNL.. Can you help? Mail me at : praveendotmv@gmaildotcom. thanks in advance