Hello Sebastien,

On Tue, 16 Mar 2010 10:04:07 +0100, "=?UTF-8?Q?S=C3=A9bastien_Lorquet?=" <squalyl@gmail.com> wrote:
>
> I know that smart card EEPROMS are rated for 100k writes, but I would not
> rely on that. In fact, this depends on how often is the EF.Kc file written,
> which was my original question. Every 30 seconds or every day? Every day is
> of course OK.

It is only written if an AUTHENTICATION REQUEST from the network is
performed. This usually happens when the phone is turned on and
does a location update. The network can also perform an AUTHENTICATION
REQUEST when doing a call or similar things, however usually this is
not done every time and the previous Kc stored on the SIM is reused
as Sylvain explained it. For OpenBSC and OpenBTS the default is that
there is no AUTHENTICATION REQUEST at all, so no Kc is written (I am
not 100% sure if this is true for OpenBTS, but I guess so).

> Additionally, how often are these other files written (LOCI, BCCH) ?

They are written when a location update is done or the cell changes.
However it depends on the phone if the data is really written to the
SIM every time, sometimes the phone caches those data and writes them
to the SIM only when the phone is turned off. For OpenBSC and OpenBTS
writing should not happen that often because there is usually only one
cell with fixed parameters. And I guess you will probably not actually
write to the EEPROM if the same data is already stored (or a least
the Card OS should do it this way).