I am using gsm-ussd to try and query my data balance from my 3G modem.
When I issue the commands
gsm-ussd -m /dev/ttyUSB0 '*188#'
gsm-ussd -m /dev/ttyUSB2 '*188#'
I get either "Device or resource busy" (when it is in used and connected) or "Unknown error (100)".
My device (Huawei E173) seems to create 3 devices in /dev, namely
ttyUSB2. None of them work, and ttyUSB1 gives a somewhat different problem, as it just give the following message:
* Wrong modem device (use -m <dev>)? * Modem broken (no reaction to AT)
UPDATE I found the following post, but I am already doing what it says: http://mybroadband.co.za/vb/showthread.php/382977-8-ta-E173-on-openSUSE-with-USSD-setup