Sierra Wireless EM7455

Ralph Plawetzki ralph at
Thu Jun 9 16:03:01 UTC 2016

Am 09.06.2016 um 17:09 schrieb Dan Williams:
> QMI and MBIM are just different ways to talk to the modem's firmware.
>  Like languages.  QMI is proprietary to Qualcomm, older than MBIM, and
> ties much more closely to the firmware architecture of Qualcomm chips.
> MBIM is a "standard" protocol that is used by many vendors, and is
> built-in to Windows 8 and later, so if a modem supports MBIM then it
> doesn't need special drivers in Windows.  It's supported by many
> vendors, regardless of what chips are in their modems.
> To make it easier to integrate into Windows, Qualcomm provided firmware
> to modem vendors that use their chips that speaks the MBIM protocol.
>  Some vendors choose to use it by default.  Some vendors also allow
> special commands to switch Qualcomm firmware between speaking QMI and
> MBIM by default.  This is what the Sierra tool that Bjorn is talking
> about does.

This is indeed very interesting. I googled a while but was not able to
find much about this topic. And none of it was that compact. Thank you!

> Only newer Sierra devices based on Qualcomm chips need this command.
>  Other vendors like Huawei, Novatel, ZTE, etc don't appear to need this
> QMI command, even if they use Qualcomm chips inside.  Not sure why
> Sierra is doing this, but they appear to be the only ones so far.

Ok. I thought it might be this way.

> If the modem's usb vendor ID is a Lenovo vendor ID, then it's a Lenovo
> customized Sierra-produced modem.  Vendors like Lenovo and HP do this
> to ensure that only approved modems are used in their own machines,
> technically to ensure that the modem and antenna solution are paired
> together.  This is theoretically for regulatory approval, since the
> modem *and* antenna are certified together, not just the modem itself.
>  Antenna can have a big effect on how the modem performs and whether it
> meets regulator requirements.  The cynical among us will say this is
> actually to ensure that users have to pay HP money for a modem instead
> of getting them on the secondary market though.

I see. I am not sure whether it says 'Lenovo' or 'Sierra' on lsusb.

Kind regards,

More information about the ModemManager-devel mailing list