[PATCH 4/4] Add a MessageWaiting interface to track message waiting indications.

[Aki Niemi]

2009/8/10 Denis Kenzior <denkenz at gmail.com>:
>> It would make sense for the providers to resend the MWI information
>> everytime subscriber connects the network and then it would be less
>> problematic in case the information couldn't be written to SIM, but I
>> don't know if they ever do this.
>
> Probably they don't, there are also weird roaming cases to consider, where you
> receive MWI, turn phone off, step on a plane and turn phone on with some other
> network entirely.

There is another case to consider when the SIM is moved to a
completely different phone. In fact, I think this is the original
reason to store the MWI flag to the SIM.

> Can we make the MWI interface smarter somehow?  Perhaps by not enabling it
> unless at least the EFmwis file is available, or by always storing the EFmwis
> contents on the filesystem?

I think this makes sense. There is another, related issue with some
Nokia modems, though. They might not support low-level, EF access
directly, but have some higher level API for accessing things like the
MWI flag, HPLMN list and SPN. We might need to think about adding such
high-level API support to the driver API as (optional) ops --
especially if other modems behave similarly -- otherwise the ISI modem
driver may need some kluge to handing EF writes.

Cheers,
Aki