You likely will not find a standalone "driver" download link for the MS2131i-8. The correct path to getting this device working is:
The Linux kernel uses the serial option driver to expose the modem's USB interfaces. If the interfaces do not load automatically upon connection, trigger them manually with the following terminal commands: huawei ms2131i-8 driver download
If your package only contains .inf , .cat , and .sys files, you must map them manually: Plug the MS2131i-8 into a USB port. Press Windows Key + X and select . You likely will not find a standalone "driver"