Re: [sim-fdn PATCH 1/4] sim: add EnableFDN and DisableFDN methods

[Denis Kenzior <denkenz@gmail.com>]

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Hi Pekka,

On 08/26/2010 11:08 AM, Pekka Pessi wrote:
> Hi Denis,
> 
> 2010/8/26 Denis Kenzior <denkenz@gmail.com>:
>>>>> Enable or disable Fixed Dialing Numbers feature on SIM card.
>>>>>
>>>>> If enabled, calls can be dialled or SMSs sent only to numbers listed on
>>>>> special FDN phonebook on the SIM card.
>>>>
>>>> FDN has serious implications for the rest of the system, particularly on
>>>> SMS atom and Sim Toolkit.  oFono will either have to support the entire
>>>> thing properly or use a 'limited' FDN mode (e.g. if FDN is enabled, we
>>>> only permit emergency calls.)
>>>
>>>> We have really not made our mind what makes sense here yet.
>>>
>>> I think most modems support FDN in the firmware. (Well, famous last
>>> words.) I don't think it makes any sense to support or "support" it in
>>> oFono.
>>
>> You're correct.  However, if FDN is enabled, carriers require that SMSes
>> to numbers not in FDN to be rejected.  It is quite unclear whether this
>> is done in the firmware or not.  If oFono has to handle it internally,
>> then we also require access to the FDN phonebook.
>>
>> Sim Toolkit interactions require FDN to be explicitly ignored for Send
>> SMS, Setup Call.  If these are not handled in the firmware, then we
>> can't properly support FDN.
> 
> Do you think oFono should reject the SIM if it happens to have FDN enabled? Why?

There is actually some 3GPP spec that mandates low-functionality mode if
FDN is not properly supported by the terminal.  e.g. 31.102:
"In case FDN is enabled, an ME which does not support FDN shall allow
emergency calls but shall not allow MO-CS calls and MO-SMS.
If BDN is enabled, an ME which does not support Call Control shall allow
emergency calls but shall not allow MO-CS calls."

> 
> If we don't support FDN restrictions, we don't support. This has
> nothing to do whether we should allow the user to disable the FDN on
> the SIM card or not.
> 

You might be right, I'm just saying we need to explore the issue more fully.

Regards,
-Denis