Make modem Huawei E397B work on Mac OS X

huawei_e397b.md

1. Install the Connection Manager that is launched when you connect the modem to the Mac
2. Download the source of usb_modeswitch from here http://www.draisberghof.de/usb_modeswitch/ (at the moment of writing this the file appears with the name usb-modeswitch-2.5.2.tar.bz2)
3. Run make in the directory of the source you downloaded
4. Run sudo ./usb_modeswitch -v12d1 -p1505 -X in the same directory

If the last step returns an error (I don't remember the error now, but I was getting an error related to usb_modeswitch not being able to take control of the modem to perfom changes):

1. Unplug the modem and plug it again
2. As soon as you plug the modem again, run sudo ./usb_modeswitch -v12d1 -p1505 -X repatedly until you get a successful result
3. Open Connection Manager and your modem is going to be detected

I got this error with commad :sudo ./usb_modeswitch -v 12d1 -p 1f01 -V 12d1 -P 14dc -J -W

libusb: error [darwin_claim_interface] USBInterfaceOpen: another process has device opened for exclusive access
Could not claim interface (error -3). Skip message sending

@LarkinZero that error is telling you that some other program is using the device. Maybe you have some driver or similar that is taking control of your USB device? If that's the case, you have to uninstall that driver or unload it, and then run usb_modeswitch.