Za účelom testovania som kúpil za pár drobných 3G modem na Aliexpresse. Jedná sa o modem osadených chipsetom Qualcomm (Qualcomm CDMA Technologies MSM). Po prvom pripojení sa hlásil ako USB zariadenie 05c6:1000 USB Mass Storage device. Postup pre spojazdnenie je tu:

https://www.raspberrypi.org/forums/viewtopic.php?t=180028

sudo apt-get update
sudo apt-get install ppp usb-modeswitch wvdial

Identify your modem

$ lsusb
Bus 001 Device 009: ID 05c6:1000 Qualcomm, Inc. Mass Storage Device 

Switch the Mode from Mass Storage Device to 3G Modem

$ sudo usb_modeswitch -W -v 05c6 -p 1000 -K

Check for changes by running lsusb again, if successful you should now see a new device ID as below:

$ lsusb
Bus 001 Device 006: ID 05c6:6000 Qualcomm, Inc. Siemens SG75
. . .

Now to make it switch automatically using Udev
Create a rule

 nano  /etc/udev/rules.d/05c6\:1000.rules

Put the following line into the empty file; It says if you see this USB device with these properties run the command we used above to switch modes from USB to 3G Modem:

ACTION=="add", SUBSYSTEM=="usb", ATTRS{idVendor}=="05c6", ATTRS{idProduct}=="1000", RUN+="/usr/sbin/usb_modeswitch -W -v 05c6 -p 1000 -K"

Save the file and reboot.
Subsequent hot plugs should see the device attached as a USB 3G modem