+CEREG signals denied before being registered

Aleksander Morgado aleksandermj at chromium.org
Thu Oct 20 08:51:54 UTC 2022


> I have another question about the Fibocom MA510-GL: When +COPS=0 is
> issued, often the modem emits the following sequence of URC which makes
> ModemManager abort the simple connect flow:
> +CEREG: 0 (idle)
> +CEREG: 2 (searching)
> +CEREG: 3 (denied)
> +CEREG: 5,... (registered, roaming)
> I guess this might not be in accordance with the specs, but I'm not
> sure. It also doesn't always do that but when it does it jumps from
> denied to registered within seconds. What would be an acceptable way to
> handle this?

That's a good question, I'm not sure what to reply here. The COPS=0
request comes from a "Register automatically" user request, or as part
of Simple.Connect(). The outcome of that operation is one single
result, we don't report back "several results". In this case, the
first "final" result we get from the modem is +CEREG: 3, so "denied",
and from my point of view, that is the result that we should probably
return, as we don't know what else will come afterwards.

If a new "Register automatically" happens after that sequence, what
does the modem do? i.e. if you run COPS=0 and we get the CEREG
idle+searching+denied+registered sequence and just after that you run
again COPS=0, does it go over all those 4 states again, or does it
return +CEREG: 5 right away?


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