bsnl broadband in ubuntu 9.10

i want to connect INTERNET in ubuntu9.10. i am able to ping in my address. i try the pppconfig and use dynamic address. also other things as default but i am not able to connect in ubuntu. also 1 year ago i try ubuntu as timepass and that time i got INTERNET working in first try. i don't know what i am doing wrong. i have bsnl home combo 199 plan. my modem is siemens c2110 (wired). also only few days ago i get a driver for my gpu so now i want to switch to ubuntu for using only original soft. please be a life Saviour. boss please provide the help in details.
thanks in advance.