Tata Plug2Surf USB modem works with wvdial and kppp(for sure and maybe with others too).
Steps for KPPP:–
1.Connect USB modem to the comp. and wait for the green light to come.
2.open terminal.
3. use “dmesg” command to check to which /dev device file is your modem mounted to ( usually its “/dev/ttyACM0″ ).
4. open kppp and select to configure it.
5.In the Accounts tab add a new account.
6.Add phone number as #777 and rest all account settings remains the same.
7.Now in the modems tab add new modem.
8.Select the device as identified using “dmesg” command.
9.Go to modems tab and open modem commands… Don’t change anything and just add “AT+CRM=1″(without the quotes) to “Initialization string 2:”.
10.Come to the main window and set both username and password as internet and just connect and enjoy 
For wvdial just connect the modem and type “wvdialconf /etc/wvdial.conf” commmand on the terminal as root.This will add the modem specific configuration to “/etc/wvdial.conf” file .After that open “/etc/wvdial.conf” in any editor and add “AT+CRM=1″ to “Init3″ and add phone number and username and password and rest all remaining same.Save and exit.To connect just type the command “wvdial” after connecting the modem and enjoy the net.
While trying both softwares i have felt that wvdial gives a better surfing speed than KPPP but it may not be true (its just a personal experience and can be a myth).
