Serial port issues on internal modem cards with Linux Kernel 3.8.x
PROBLEM: The newer Linux kernels >= 3.8 cause problems with serial ports on Multi-Tech's internal modem cards, such as corrupt data, missing ports, general serial control failures. SOLUTION: Use Linux kernels prior to 3.8 (e.g. 2.6.x or 126.96.36.199.51) instead until the kernel issues are resolved. If running an LTS Ubuntu release (12.04), there is the option of running a few different kernel versions. Here is a link to package names that reference LTS kernel back ports: http://packages.ubuntu.com/search?keywords=linux-image-generic-lts&searchon=names&suite=all§ion=all Example: If you are running Ubuntu 12.04 with kernel 3.8, then the linux-image-generic-lts-raring is installed, which is a back port of the kernel from Ubuntu raring to precise (12.04). You can remove the 3.8 kernel and install linux-image-generic-lts-quantal (3.5) using the software update, this way the kernel is changed without changing the Ubuntu release.