Storage behaviour when sending SMS

[Ulrich Mohr]

Hey,

>>
>>> while trying to resolve the issue when sending SMS with specific 
>>> mbim modems 
>>> (https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/562), 
>>> I see different behaviour when sending SMS depending on the modem I 
>>> use:
>>>
>>> When I send an SMS using a non-MBIM modem (UBlox Toby L210, RNDIS), 
>>> the SMS is shown (using mmcli) as sent. When I then restart 
>>> ModemManager, the SMS is no longer there. So it seems that the 
>>> message is not stored in SIM or modem.
>>> When I send an SMS using my MBIM modem (Telit LE910C1-EU), the SMS 
>>> is shown (using mmcli) as sent. When I then restart ModemManager, 
>>> the SMS is still there. So it seems that the message is stored 
>>> immediately when sending (to be precise: Any attempt to send the SMS 
>>> creates an entry in the SMS storage on this modem -- so when I have 
>>> three attempts to send an SMS, two failed and the third succeeded, I 
>>> have two drafts and on sent message in the storage (!?) )
>>>
>>> Is ModemManager capable to handle both of these scenarios? It seems 
>>> to me that ModemManager does not expect the second scenario, which 
>>> leads to the issue when deleting messages...
>>>
>> The SMS management in the MBIM protocol is extremely bad. There is no
>> notion of SMS storages or no action to explicitly store SMS messages.
>> Any SMS management operation on devices using the MBIM protocol
>> exclusively is really far from ideal.
>
> [...]
>
> Another possibility (just for my case) would be to delete all sent SMS 
> each time after sending. But there is no support for that in mbimcli, 
> although the MBIM protocol includes such a command. Do you have some 
> guidance where to start if I want to implement it?

I managed to implement bulk-delete in mbimcli using the appropriate 
commands. Of course ModemManager has no chance to get the information 
that the messages have been deleted and still shows them when using 
--messaging-list-sms.

So the question is whether we can support these bulk commands in 
ModemManager -- then ModemManager knows that the messages have been 
deleted and can update its internal state of the SMS messages. That 
would be a nice thing anyway, because it is quite painfull to delete SMS 
messages one by one using mmcli (Script can of couse be used, but this 
is quite inefficient and takes quite long compared to using the bulk 
commands). And as far as I can see, AT commands also support that.

What do you mean?

-- 

Best regards / Mit freundlichen Grüßen / Salutations distinguées

Ulrich Mohr

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