AW: 5G connection establishment

Federico Murciano Federico.Murciano at
Tue Sep 29 14:40:31 UTC 2020

Si Sebastian,

When I run the at+qeng=”servingcell” command with mmcli as:

sudo mmcli -m 0 --command=at+qeng=”servingcell” 

I get the following error:

GDBus.Error:org.freedesktop.ModemManager1.Error.Connection.NoCarrier: No carrier'

Do you know why am I getting it?

Thank you!

Federico Murciano
B.Sc. Telecommunications Engineer
federico.murciano at
Tel. +49 (0) 30/314 -74 025
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Technische Universität Berlin
Fakultät IV – Elektrotechnik & Informatik Sekretariat TEL 14 Ernst-Reuter-Platz 7
10587 Berlin, Germany

DAI-Labor - Distributed Artificial Intelligence Laboratory Chief Executive Director: Prof. Dr. Dr. h.c. Sahin Albayrak

Von: Sebastian Sjöholm <sebastian.sjoholm at>
Gesendet: Dienstag, 29. September 2020 05:37
An: Nick B
Cc: Federico Murciano; modemmanager-devel at
Betreff: Re: 5G connection establishment


When using NSA (ENDC) the anchor will always be LTE, so for the modem LTE will be the primary network.

The NR will only be used for the user plane, and activated only during data session, but even during data session signalling (control plane) will be on LTE.

Depending on network setup, the NR session will be disconnected right after the data session. At some it can be instant, other might have longer timeouts.

On RM500 you can check with at+qeng=”servingcell” and on SIM8200 at+cpsi? to see if the additional NR cell is connected after or during data session.



> On 29 Sep 2020, at 00:21, Nick B <nickberry17 at> wrote:
> Hey,
> Just for the record, I am having the excat same experience in Australia with at Quectel RM500Q-GL and SIMCOM SIM8200EA-M2.  Is there any debugging info that would be helpful?
> Best,
> Nick
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> ModemManager-devel at

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