Huawei ME909s-120 registration denied

[Reinhard Speyerer]

On Wed, Mar 28, 2018 at 09:43:20AM -0500, Dan Williams wrote:
> On Tue, 2018-03-27 at 14:28 +0100, Hugh Warrington wrote:
> > On 16 March 2018 at 22:51, Dan Williams <dcbw at redhat.com> wrote:
> > 
> > > On Wed, 2018-03-14 at 16:41 +0000, Hugh Warrington wrote:
> > > > 1. Is registration denied a recoverable error -- and if so should
> > > > I
> > > > expect
> > > > modemmanager to retry registration?
> > > 
> > > It's recoverable to the extent that you can attempt to manually
> > > register with another network, or you could airplane-mode-then-
> > > retry
> > > registration to the same network and see if it works, or you could
> > > change the preferred access technology.  But usually, if the
> > > network
> > > denies you, that same network will deny you again.
> > > 
> > 
> > I've written a script to repeatedly reset the modem and see if
> > registration
> > succeeds. After hundreds of trials I've found that registration seems
> > to
> > succeed or fail at random in this case.
> > 
> > It doesn't make sense to me, and having spoken to the network it
> > makes no
> > sense to them either. I had a support call in which they performed a
> > 'live
> > trace'. On the attempts where registration was denied they saw
> > nothing
> > whatsoever in their logs (not even a connection attempt) and the
> > support
> > call ended with a big shrug.
> > 
> > What's more, some SIMs from the same provider display this
> > intermittent
> > failure mode while others work every time. But putting the SIMs in a
> > different device with a Quectel modem, they work every time. So the
> > problem
> > seems to be the combination of modem model and SIM (for completeness
> > I also
> > tested in other identical instances of the same modem/PC, with the
> > same
> > results).
> 
> Yeah, sounds plausible.  For another example, various Icera chipset
> based modems don't work with some SIMs that include ISIS/Softcard
> support, which Icera confirmed to me was a firmware issue.  Other SIMs
> and modems worked fine.  So it definitely can happen :)
> 
> > From what you say it sounds like registration denied shouldn't be a
> > 'routine' failure mode. But is there any option to have modemmanger
> > automatically retry? If not then I will just write a cron job to
> > detect
> > registration denied and reset the modem.
> 
> MM doesn't have a way to automatically reset the modem periodically if
> registration is denied, because we've never encountered this kind of
> situation before.  But we could potentially add a timer to retry after
> a couple minutes or something.
> 
> > (as an aside, there are tables in the SIM card that control how
> > > automatic registration works; it could be that your operator is
> > > perhaps
> > > denying registration to the UMTS network but would allow LTE and
> > > the
> > > SIM doesn't distinguish the two.  Or something like that...  but
> > > this
> > > would be odd.)
> > > 
> > 
> > That sounds exactly the kind of mistake they might make. Any idea
> > if/how I
> > can access that SIM state?
> 
> What you can do is access SIM tables and the SIM filesystem with
> AT+CRSM and such.  The problem is that you then get to decode the SIM
> response manually, and that I have no idea which tables might be
> interesting to look at.  It's fairly easy to get the information out;
> figuring out what it means is the time-consuming thing.  If you're
> interested in doing that, I might be able to point you in a direction.

Hi,

EF_LOCI and optionally also EF_PSLOCI probably contain the most useful
information regarding network registration.

Given that no registration attempts could be seen in the 'live trace'
in the network when the ME909s-120 reported a 'registration denied'
status and that the problem could not reproduced with a Quectel modem
this looks like a potential ME909s-120 firmware proplem to me which
only happens under specific circumstances/timing conditions.

My suggestion would be to check that the ME909s-120 runs the latest
released firmware version and perform a firmware update if it does not.

In case the 'registration denied' problems persist with the latest
firmware version the next step would probably be to ask the distributor
about a tool for logging the information on the diagnostics/trace port
of the mobile so that they can be forwarded to Huawei for analysis.

Huawei used to have such a tool for their Qualcomm-based devices,
perhaps there is something similar for HiSilicon-based devices like the
ME909s-120.

Regards,
Reinhard