Ubuntu 8.10 and the Sony Ericsson MD300 modem

November 17, 2008

Since the 3G network is growing fast here in Brazil I decided to give it a try. My carrier offered me a Sony Ericsson MD300 modem as part of the service. Then I had the mission to make it work under Linux, in specific the Ubuntu 8.10 (my current distribution).

The MD300 modem is not officially supported but as I will show bellow, it is quite well compatbile with the Ubuntu 8.10. This USB device comes with 3 different operation modes. The defaul mode is the 1, which the device acts like a flash drive and of course we are not interested. Then we have to tell the Linux to switch to the mode 3 (serial modem) when the new device is plugged. To do so, we create an udev rule. It is quite easy.

Create a udev rule’s file (on the /etc/udev/rules.d) for the device

sudo gedit /etc/udev/rules.d/50-md300modem.rules

Then put the following content on the rule’s file:

ACTION!=”add”, GOTO=”3G_End”
BUS==”usb”, SYSFS{idProduct}==”d0cf”, SYSFS{idVendor}==”0fce”, NAME=”%k”,SYMLINK=”modem3G-%n”, PROGRAM=”/bin/sh -c ‘echo 3 > /sys/%p/device/bConfigurationValue'”

Be careful with the like breaks. The text above has only 3 lines.

After those steps, reboot your machine so the new rules can be applied and connect your modem at an USB port. Now it should be working and two devices must have appeader (/dev/ttyACM0 and /dev/ttyACM1)