The following test was made on Gentoo Linux. I copied it here from google search results for your reference (because all of the links contain this article are not stable links and probably gone after 1 year or so).

I myself run it fine on Ubuntu Linux.

This is a Korean product.

Linux 2.6.16-gentoo-r2 x86_64 AMD Athlon(tm) 64 Processor 3400+ GNU/Linux
5188 USB CDMA 1x Moderm
ppp wvdial

emerge ppp wvdial

usermod -aG dialout

wvdialconf /etc/wvdial.conf
editing `/etc/wvdial.conf'.
Scanning your serial ports for a modem.
ttyS0<*1>: ATQ0 V1 E1 -- failed with 2400 baud, next try: 9600 baud
ttyS0<*1>: ATQ0 V1 E1 -- failed with 9600 baud, next try: 115200 baud
ttyS0<*1>: ATQ0 V1 E1 -- and failed too at 115200, giving up.
ttyS1<*1>: ATQ0 V1 E1 -- failed with 2400 baud, next try: 9600 baud
ttyS1<*1>: ATQ0 V1 E1 -- failed with 9600 baud, next try: 115200 baud
ttyS1<*1>: ATQ0 V1 E1 -- and failed too at 115200, giving up.
Modem Port Scan<*1>: S2 S3
ttyACM0<*1>: ATQ0 V1 E1 -- OK
ttyACM0<*1>: ATQ0 V1 E1 Z -- OK
ttyACM0<*1>: ATQ0 V1 E1 S0=0 -- OK
ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 -- OK
ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 -- OK
ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
ttyACM0<*1>: Modem Identifier: ATI -- ERROR
ttyACM0<*1>: Speed 4800: AT -- OK
ttyACM0<*1>: Speed 9600: AT -- OK
ttyACM0<*1>: Speed 19200: AT -- OK
ttyACM0<*1>: Speed 38400: AT -- OK
ttyACM0<*1>: Speed 57600: AT -- OK
ttyACM0<*1>: Speed 115200: AT -- OK
ttyACM0<*1>: Speed 230400: AT -- OK
ttyACM0<*1>: Speed 460800: AT -- OK
ttyACM0<*1>: Max speed is 460800; that should be safe.
ttyACM0<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0 -- OK
Found an USB modem on /dev/ttyACM0.
/etc/wvdial.conf: Can't open '/etc/wvdial.conf' for reading: No such file or directory
/etc/wvdial.conf: ...starting with blank configuration.
Modem configuration written to /etc/wvdial.conf.
ttyACM0: Speed 460800; init "ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0"

nano -w /etc/wvdial.conf

[Dialer Defaults]
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Modem Type = USB Modem
Phone = #777
ISDN = 0
Username = CARD
Init1 = ATZ
Password = CARD
Modem = /dev/ttyACM0
Baud = 460800

modprob ppp
wvdial

--> WvDial: Internet dialer version 1.56
--> Cannot open /dev/ttyACM0: Input/output error
--> Initializing modem.
--> Sending: ATZ
ATZ
OK
--> Sending: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
OK
--> Modem initialized.
--> Sending: ATDT#777
--> Waiting for carrier.
ATDT#777
CONNECT
--> Carrier detected. Waiting for prompt.
~[7f]}#@!}!}!} }=}!}$}%j}"}&} } } } }#}%B#}%}%}&} oOb}'}"}(}"Hn~
--> PPP negotiation detected.
--> Starting pppd at Fri Apr 21 17:34:53 2006
--> Pid of pppd: 11116
--> Using interface ppp0
--> pppd: 5+
--> pppd: 5+
--> pppd: 5+
--> pppd: 5+
--> local IP address 220.205.12.112
--> pppd: 5+
--> remote IP address 220.192.8.6
--> pppd: 5+
--> primary DNS address 220.192.8.58
--> pppd: 5+
--> secondary DNS address 220.192.32.103
--> pppd: 5+

I tried this product on Ubuntu 7.10. Maybe on Gentoo it involve so many steps as described above, but in Ubuntu it's very easy.

1. Plug the device into a USB slot;
2. in "Administration" -> "Network Setup", you can see a modem connection not activated. Click to edit its properties.
3. In properties, fill "#777" as telephone number for China Unicom, "CARD" for username and "CARD" for password. If you are using other ISP please ask them the telephone number, username and password.
4. Click another tab in properties to set this connection to use DNS server provided by ISP and use the connection as default route, these two options are for China Unicom, if you use other ISP please consult them.
5. Close properties dialog, and check the checkbox before modem connection to activate it. Close everything, after a while you will be able to surf the internet.

Note you can also add "Network Monitor" applet to gnome panel to be able to track the status of the connection, so you can spot it if connection is dropped.

Second note: here is a photo of this product in case you are not sure if it's what you have on hand:
http://www.taobao.com/view_image.php?pic=Wx0GGlFDXA1VUwMGWx0SCwkNGVxbVl8cVllcRgcaBwMSAF1QHFtBRkFUW1tHQggBHQIACBw9Q0Q0GBI8XmtRUAEtQhEbBi5cUklV&d=1&title=uqu5%2BiCyqMDWIEJPUkEgNTE4OCBVU0K907%2FaIENETUEgzt7P38nPzfi%2FqA%3D%3D&version=2&c=ZDE1Y2M2ZjhlOGEzMjQ1MzI1MDg4MDczNGMwZWNjN2M%3D

I just wish to add to my previous comment: you need to set "/dev/ttyACM0" as the modem device in the modem connection properties dialog, it's important to keep this correct!