Huawei E1752 Mobile Broadband USB key

Before leaving on vacation, I wanted to be sure I would be able to connect to the internet, using the wireless USB key I have used at the office some time ago, for a project.

This is an operator-branded key, delivered with a dedicated piece of software, which is supposed to help you use the key. The fact is that this software works quite well, but... it was developed for Microsoft Windows. While I want to use the key on Linux.

On the laptop I'll use, I have Linux Mint 10 (which is based on Ubuntu 10.10).

The USB key is a Huawei E1752. First step: connect it to the PC. It is immedialty recognized by the network manager. So I try to create a new mobile broadband connection, using network manager wizard, providing the PIN code, choosing the operator, the contract, etc.

But the connection does not accept to be activated. I try several APN. Still same problem: the connection does not want to start...

So, I decide to perform some diagnostics. The USB key is seen as a modem by Linux, and it is possible to request its status by sending it AT commands.

The first step is to find which device is to be used. Quite easy to find: in the /dev directory, there are a /dev/ttyUSB1 directory and a /dev/ttyUSB2 directory, created a few minutes ago, when I connected the key to the PC. 

Second step: install a communication program. Using Synaptic, I install Minicom, and configure it to use /dev/ttyUSB1 port, save this configuration to Minicom configuration file, and restart it. Minicom is run using sudo, so that there is no problem with device access rights.

Now, I should be connected to the key. Let's try entering a first AT command: ATE1 (this command requests the key to echo every character it receives). I get back OK. Which is very positive .

Second command to enter: AT+CGATT? (this command asks the key whether it is attached to the mobile network). The answer is: +CGATT: 0. Which means that the key is not attached to the network. So, I request the attachment: AT+CGATT=1. And the answer is: ERROR. Well, well, well... If I can't attach to the network, it could mean that the SIM is no more valid. Just to check, I type this command: AT+CGREG? which requests network registration status. The response is: +CGREG: 0,3. Which means: registration denied... OK, I have to use another SIM card...

So, I replace the SIM card with an active one. And... it works. Cool, I can leave on vacation