[sudeep@myhost ~]$ lsusb
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 004 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 004: ID 1c4f:000e SiGma Micro 
Bus 001 Device 003: ID 0a5c:21b2 Broadcom Corp. 
Bus 001 Device 004: ID 0408:2fb1 Quanta Computer, Inc. 
Bus 002 Device 005: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse
Bus 002 Device 007: ID 1c9e:9605 

modprobe cdc_acm
modprobe usbserial vendor=0x1c9e product=0x9605

[root@myhost etc]# ls /dev/ttyUSB*
/dev/ttyUSB0  /dev/ttyUSB1  /dev/ttyUSB2

[root@myhost etc]# wvdial bsnl
--> Sending: ATDT*99#
--> Waiting for carrier.
ATDT*99#
CONNECT 7200000
--> Carrier detected.  Starting PPP immediately.
--> Starting pppd at Mon Nov 28 07:48:02 2011
--> Pid of pppd: 2448
--> Using interface ppp0
--> Disconnecting at Mon Nov 28 07:48:32 2011
--> The PPP daemon has died: A modem hung up the phone (exit code = 16)
--> man pppd explains pppd error codes in more detail.
--> Try again and look into /var/log/messages and the wvdial and pppd man pages for more information.
--> Auto Reconnect will be attempted in 5 seconds
--> Cannot get information for serial port.
--> Initializing modem.
--> Sending: ATZ
ATZ
OK
--> Sending: at+cgdcont=1,"ip","bsnlnet"
at+cgdcont=1,"ip","bsnlnet"
OK
--> Modem initialized.
--> Cannot get information for serial port.
--> Initializing modem.
--> Sending: ATZ
ATZ
OK
--> Sending: at+cgdcont=1,"ip","bsnlnet"
at+cgdcont=1,"ip","bsnlnet"
OK
--> Modem initialized.
--> Sending: ATDT*99#
--> Waiting for carrier.
ATDT*99#
ERROR
--> Invalid dial command.
--> Disconnecting at Mon Nov 28 07:48:37 2011