Hi Vikas,
I had the same problem and i followed what is said in the link which you had given. Still the problem persists. here is what i do:
root@Vino:~# wvdialconf
Editing `/etc/wvdial.conf'.
Scanning your serial ports for a modem.
Modem Port Scan<*1>: S0 S1 S2 S3 S4 S5 S6 S7
Modem Port Scan<*1>: S8 S9 S10 S11 S12 S13 S14 S15
Modem Port Scan<*1>: S16 S17 S18 S19 S20 S21 S22 S23
Modem Port Scan<*1>: S24 S25 S26 S27 S28 S29 S30 S31
WvModem<*1>: Cannot get information for serial port.
ttyUSB0<*1>: ATQ0 V1 E1 -- failed with 2400 baud, next try: 9600 baud
ttyUSB0<*1>: ATQ0 V1 E1 -- failed with 9600 baud, next try: 9600 baud
ttyUSB0<*1>: ATQ0 V1 E1 -- and failed too at 115200, giving up.
Sorry, no modem was detected! Is it in use by another program?
Did you configure it properly with setserial?
Please read the FAQ at
http://alumnit.ca/wiki/?WvDial