if u r using K750i then u are already half done.. ur pc must have two or three modems installed when u first connected ur phone... now create a new dial up connection >> connect ot the internet>>use dialup modem>>choose manually>>enter any name>>usernae and pass blank>>phone no *99#
one more thing goto control panel>phone and modem options>select the modem u are using.. goto its properties>choose any speed btwn 115200 to 960000> then in advanced sttings paste the following in AT initialization at+cgdcont=1,"IP","airtelgprs.com"
hope it helps!