$ dmesg | grep tty
[    0.000000] console [tty0] enabled
[    1.131606] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a NS16550A
[34786.069681] cdc_acm 1-4:1.7: ttyACM0: USB ACM device

# cat /etc/wvdial.conf 
[Dialer Defaults]
Modem = /dev/ttyACM0
Init = AT+CGDCONT=1,"IP","internet"
Phone = *99#
Stupid Mode = 1
Username = " "
Password = " "

 # wvdial
--> WvDial: Internet dialer version 1.61
--> Cannot get information for serial port.
--> Initializing modem.
--> Sending: AT+CGDCONT=1,"IP","internet"
AT+CGDCONT=1,"IP","internet"
OK
--> Modem initialized.
--> Sending: ATDT*99#
--> Waiting for carrier.
ATDT*99#
CONNECT
~[7f]}#@!}!} } }2}#}$@#}!}$}%\}"}&} }*} } g}%~
--> Carrier detected.  Starting PPP immediately.
--> Starting pppd at Sat Dec  1 20:23:09 2012
--> Pid of pppd: 4547
--> Using interface ppp0
--> pppd: øîx·àϜ p˜ [01]
--> pppd: øîx·àϜ p˜ [01]
--> pppd: øîx·àϜ p˜ [01]
--> pppd: øîx·àϜ p˜ [01]
--> local  IP address 10.224.51.174
--> pppd: øîx·àϜ p˜ [01]
--> remote IP address 10.6.6.6
--> pppd: øîx·àϜ p˜ [01]
--> primary   DNS address 62.241.198.245
--> pppd: øîx·àϜ p˜ [01]
--> secondary DNS address 62.241.198.246
--> pppd: øîx·àϜ p˜ [01]

$ ifconfig | grep -A2 ppp0
ppp0      Link encap:Point-to-Point Protocol  
          inet addr:10.224.51.174  P-t-P:10.6.6.6  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1