Informations about mobile connection


Do we have a command that can show us which baseband the mobile connection of the Librem 5 is currently using ?

I tried mmcli -m <id> but the current bands are equal to the supported ones and have different names compared to the baseband tables

any idea ?

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The question about how to find out which bands are used was discussed here, but then nobody seemed to know the answer:

I suspect that it could be something that only the modem knows internally, that the ModemManager software never gets to know about that. At least as far as I know there is no way of checking which ban is used.

You can tell it to use only a subset of the supported bands, so I guess you can be certain that a specific band is used if you set that band as the only allowed (current) band. I mean, if you do the experiment of setting a single band as the only current band and then trying to use the mobile connection, then it will either not work (because that band is not possible to use at your location) or it will work and then you know it is using that specific band because it is the only one it is allowed to use.

Edit: of course what we really want is a modem that uses free firmware, then we could easily find out this kind of things. But I guess no such modem is available.


In Android, there are apps that can reveal the band in use:

But you probably can’t assume an L5 is using the same band as an Android at the same location, given that different phones/modems have different frequencies baked in. It might be possible to narrow it down by process of elimination: comparing the Android’s operating bands with the L5’s operating bands, and the carrier’s available bands at the given location. Or not…?

For iPhones, see:

Since the frequency (band) in use can change all the time, mostly as a result of moving but also in theory as a result of network changes, there are two possibilities.

  1. The modem can and does report that to the host. In that case ModemManager could know, but it really isn’t all that relevant (provided that things are working).
  2. The modem does not report that to the host. In that case ModemManager could not know (unless it polls). So you would have to ask the modem directly (with the understanding that the information could be out of date by the time that you look at it).

The situation is somewhat similar to, say, the signal strength - which you can enquire about.

For the Broadmobi modem, as we don’t have even remotely acceptable documentation of the modem (AT) commands, we have no idea how to ask the modem. Maybe it’s possible but we don’t know the command. Maybe it isn’t even possible.

Maybe the situation will change if and when customers get the Gemalto modem.

Yes, indeed. In our dreams. (It also means that we could audit the modem for backdoors, fix bugs, make enhancements, …)

You could buy a multi-channel spectral analyser and listen for the Librem 5’s transmissions. :rofl:

Thanks for your answers… and damn it…
I’ll may try to script the filtering tests of bands, if one day the motivation comes, starting with identifying the names provided by mmcli

There are some projects about open firmware used on GSM modem, last time I heared about, it was very basic and experimental on one phone/modem