(Out of topic) MiniPCI <->USB adapter with dual sim slot?

[Dan Williams]

On Wed, 2014-02-26 at 12:56 +0100, Bjørn Mork wrote:
> Aleksander Morgado <aleksander at aleksander.es> writes:
> 
> > Does anyone know where I can get a miniPCI<->USB adapter with dual SIM
> > slot? A quick google search gave me no results; but there are likely
> > 'dev kits' from manufacturers that I don't know of... Can someone get me
> > one? :)
> 
> I am wondering how you'd want that to work?  What's the use case?
> 
> Maybe you can achieve what you want by using a dual SIM adapter (google)
> with a standard miniPCIe<->USB adapter?  You may have to implement STK
> support in libqmi and ModemManager to use it, but that would be nice
> anyway :-)

Dual-SIM seems to be pretty common in India and Asia and its purpose is
to reduce cost of service or for convenience.  Three cases I can think
of:

1) you travel between areas a lot; you don't need to insert/remove SIMs
every time, you simply put two SIMs in the phone and you can select
which provider to use.

2) some services are cheaper with one provider and others are cheaper
wtih another provider; dual-SIM allows you to pick which provider you'd
like to use for any specific function

3) same phone, two numbers; you don't have to carry both work and
personal phones with you

Dual-SIM devices have different levels of functionality.  Loosely from
Wikipedia:

Dual SIM Single Standby (DSSS): SIM switching, where both SIMs are known
to the device, but only one is actually active at any given time, and
only one radio network can be attached.  The user must manually switch
between the SIMs.

Dual SIM Dual Standby (DSDS): both SIMs are actually attached to
different networks, but only one SIM can be active (receive or originate
a call or data connection) at a time.  When a call is active with one
SIM, the other one is detached and cannot make or receive calls or data
connections.

Dual SIM Dual Active (DSDA): the device has two RF paths and two modem
stacks, so everything can be simultaneous.  When originating a call or
sending an SMS, you get to pick which SIM you want to use.  Data can be
active on both networks at the same time too.  Some devices may only
support this on 2G/3G instead of allowing 3G/3G.  Battery also
(obviously) sucks.

Dan