Problem using an APN with 4G not available

Sun Nov 8 07:45:03 UTC 2020

Thank you Paul, I will give a try, in fact the impossible lte connection to
the custom APN has been confirmed by our service provider. This is a issue
that should be fixed by my customer with service provider, by paying more
money.
Once again, thank you for your kind help.

Il giorno sab 7 nov 2020 alle 23:18 Paul Bartell <p.bartell at tempered.io> ha
scritto:

> Giovanni,
>
> I’ve encountered a similar problem with a Quectel EC25 (and Telit
> LE910C4-NF) modem where a custom apn was only allowed to connect on LTE as
> the default EPS bearer. Without changing the default eps bearer apn setting
> to match the custom apn, the modem fails to register on the network and
> falls back to 3G.
>
> You might try modifying the APN setting of the default EPS bearer with
> qmicli wds-modify-profile (usually the first profile) and checking if you
> can connect to LTE that way.
>
> You might also try using a blank apn setting in profile #1 if your modem
> has a carrier profile with a default bearer apn set. Setting this value to
> an empty string will cause the modem to use the network provided apn
> setting.
>
> Hope this helps,
> Paul
>
> > On Nov 7, 2020, at 1:21 PM, Giovanni Parodi <giovanniparodi79 at gmail.com>
> wrote:
> >
> > Thank you, you are right, I verified today.
> > There are 2 different reply from APN: “unsubscribed option” when I use a
> SIM that doesn’t support LTE option (didn’t pay for it) or “unknown-apn”
> when the sim could connect to lte, but the APN doesn’t support it. I should
> support it downgrading connectivity to umts|gsm and everything works fine.
> > Stupid error from my side, I was sure there should be an automatic
> downgrading to LTE as it happens when you have a not powerful enough
> signal, but this a different issue, and it should be managed by the SW
> developer. Thank you for your great help
> >
> > Il giorno sab 7 nov 2020 alle 17:59 Aleksander Morgado <
> aleksander at aleksander.es> ha scritto:
> > Hey,
> >
> > > Good morning, I'm a user of libqmi and qmicli tool and I need some
> help.
> > > I'm using a SIM of an Italian provider (TIM), configured on a standard
> private APN (the SIM and APN are of a customer of my company, he pays for a
> custom APN to the TIM company).
> > >
> > > When using the standard public APN (ibox.tim.it), with a modem that
> supports LTE connectivity (Quectel EC25), I can go online and get a
> connection to the network.
> > > If I configure the custom private APN (that uses the same network
> infrastructure), I'm able to connect to the (private) network and to go
> online, pinging the private customer server, only if a set the modem as 3G
> using the command line:
> > >
> > > qmicli -d /dev/cdc-wdm0
> --nas-set-system-selection-preference="umts|gsm"
> > >
> > >
> > > If I configure the SIM as:
> > >
> > > qmicli -d /dev/cdc-wdm0
> --nas-set-system-selection-preference="lte|umts|gsm"
> > >
> > >
> > > I receive the error:
> > >
> > > <<<<<<   type       = "Call End Reason" (0x10)
> > > <<<<<<   length     = 2
> > > <<<<<<   value      = F5:03
> > > <<<<<<   translated = gsm-wcdma-unknown-apn
> > > <<<<<< TLV:
> > > <<<<<<   type       = "Verbose Call End Reason" (0x11)
> > > <<<<<<   length     = 4
> > > <<<<<<   value      = 06:00:1B:00
> > > <<<<<<   translated = [ type = '3gpp' reason = '27' ]
> > >
> > >
> > > Here is my problem: if I use the SIM in a smartphone, the smartphone
> fails connection in lte mode but after a few seconds (about 30) goes to
> UMTS mode and gets its address.
> > > My problem is that, even if I select to support umts,LTE,GSM, when the
> modem tries connecting, it tells me unknown-apn, and does not switch to
> UMTS connectivity option.
> > > If I use 3G mode, everything works fine.
> > > So here is my question: how should I manage this kind of problem?
> > > How can I force qmicli to manage switching at connection time
> different mode search of APN?
> >
> > If you know in advance that you're going to hit the situation, I
> > assume you could run the qmicli commands to prefer (or even limit) 3G
> > depending on the specific APN to use? Or, otherwise, just assume that
> > if you ever get the "gsm-wcdma-unknown-apn" call end reason you should
> > think of falling back manually to 3G and retrying.
> >
> > > I know this may be a simple issue for expert people, but I'm really
> confused.
> >
> > I am no expert on the inner LTE stack details, so I cannot comment
> > much more I'm afraid. This could also be a lack of planning in the
> > operator side, for what it's worth; i.e. why does the APN get reported
> > as unknown when using the LTE infrastructure? Is that a known
> > limitation of that APN?
> >
> > --
> > Aleksander
> > https://aleksander.es
> > _______________________________________________
> > libqmi-devel mailing list
> > libqmi-devel at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/libqmi-devel
>
>
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