Setup of Huawei MSI2131i

I just got a Huawei MSI2131 and am trying to use it (on an Intel Edison, Yocto distribution). The device shows up as 12d1:1506 Huawei … E398 LET/UMTS/GSM Modem/Networkcard.

But there is no /dev/ttyACM0, nor is there /dev/ttyUSB0 to work with when I boot up with this device attached.

I tried the standard modeswitch command, but got this response: Error: can’t use storage command in MessageContent with interface 0; interface class is 255, expected 8. Abort.

So then I tried just forcing the driver to deal with the Huawei in its original state,
echo 12d1 1506 > /sys/bus/usb/drivers/cdc_acm/new_id

This did create /dev/ttyACM0 and I could launch a PPP link on it. But there was also an information/warning message from the driver, something like

cdc_acm 1-1:1.1 This needs exactly 3 endpoints

(and indeed, I would have expected to see /dev/ttyACM0, /dev/ttyACM1, /dev/ttyACM2 but only got the first).

Is there something I am missing?

On my raspberry-pi, it wasn’t a usb0 device. I checked with dmesg which device it was.

Also note that the modeswitch is only needed for hilink devices. Not sure if yours is!

The only USB serial driver I could find on the Edison was PL2303, but I guess I could try that instead to see if it will create ttyUSB0, etc.

One other question I have. I notice the MS2131 has a small port on the side, looks like it might be for an external antenna. Is this documented anywhere? I saw at another vendor this quote:

In addition to the built-in diversity antenna the MS2131 also has the possibility to be connected to an external antenna via its CRC9 connector.

Sure enough, there are many external antenna products with CRC9 connectors, but which is appropriate for the MS2131 on the Hologram network? Should I be looking for 3G/4G, LTE or what?

MS2131 only supports 2G and 3G so you can limit your search to those.