Getting an XT USB Modem working in Ubuntu

Given that I’m rocking Ubuntu 10.04 on my beloved ASUS EEE 1005PE, I had a need to be able to use my Telecom XT T-Stick (a.k.a. ‘ZTE Corporation MF636 HSUPA USB Modem’) via Ubuntu.

The issue with these particular devices is that they respond to the system by default as a CD drive or USB hub so Ubuntu (with the stick in it’s native form) doesn’t see it as a modem device.

To turn off the function, and make the device a nice simple USB modem, you can do some jiggery pokery using ‘usb_modeswitch’ to switch off the autorun feature…

OR

you can send the AT command “AT+ZCDRUN=8” to the modem.

I chose option two and used a windows machine with a terminal client, but for anyone wanting to avoid using windows, you can achieve the same result^* using minicom (sudo apt-get install minicom)

^*let me know if you choose to do this as it’d be nice to include the command lines used for completeness of this guide.

On the Windows machine:

Get the COM port where the device is sitting

Right click on ‘My Computer’ icon on your desktop and select ‘Properties’
	Select ‘Device Manager’ from the list in the top-left corner of the screen that opens and accept any warnings relating to starting the management console
Click the + sign next to ‘Ports (COM & LPT)’ to expand the list and look for the USB modem which should be something similar to what is show in the image.

You can then use Hyper Terminal or any other program which will give you access to the USB modem device and allow you to send control strings.

I’m using RealTerm (my installation of Windows was lacking Hyper Terminal), but the configuration and control strings are the same regardless of what you end up using.

Running RealTerm

For some reason, I was getting errors starting RealTerm as a standard user, thus I found it was necessary to run as Administrator – of course, your mileage may vary
	Check the values of the COM port where the US Modem is located are as follows: 115200 – Bits per second 8 – Data bits None – Parity 1 – Stop bits None – Flow Control Then click ‘Change’ – this should connect to the device.
Click the ‘Send’ tab and enter the following control string: AT+ZCDRUN=8 And click ‘Send ASCII’ You may not see any response, but once completed, you should be able to extract the device from your Windows machine and insert it into your Linux box.

NOTE: If you need to restore the multifunction option (e.g. you plan to use the device on a new windows machine and want the drivers to be loaded from the TStick) you will need to repeat the steps above, and send the AT command:

AT+ZCDRUN=9

On the Ubuntu machine

Once the T-Stick has been inserted into your Ubuntu machine, right click on the network indicator and ‘Enable Mobile Broadband’
	Once the device indicator is blue you should be able to left-click the network indicator and create a ‘New Mobile Broadband (GSM) Connection’

From here on in, things are pretty obvious:

Click ‘Forward’ to start the wizard Select your providers country Select the specific provider from that country Choose the billing plan Complete the wizard

All things being equal, you should then be connected to the Mobile network via your T-Stick and you’ll be able to enjoy is speedy speeds of Telecom XT on your Ubuntu laptop.

Happy mobility!