PNLM list overwritten

Kevin Redon ml at
Sat Sep 8 16:21:52 UTC 2012


Curious, but I tested it and also came to the same conclusion (with a current vodafone card).
The changes on PLMNsel are not stored permanently. On the next power up, the SIM will rewrite this file.
Here some code to test it: 
The source is open (it uses libpcsc), but only use it to verify the results (e.g. not distributing it), as the code is not yet ready to be published (the file will be removed in 2 days).

have fun,

Excerpts from Dario Lombardo's message of Fri Sep 07 23:12:45 +0200 2012:
> On Fri, Sep 7, 2012 at 6:02 PM, Brandon Creighton <cstone at> wrote:
> > I've seen similar behavior before -- particularly trying to write
> > EF.PLMNSEL, EF.FPLMN, and EF.{O,H,}PLMNwACT on some US-carrier SIMs.
> >
> > This seems to be worse in the ones from AT&T MVNOs (I've tried ones
> > from Red Pocket and H2O).  Generally, the write just fails; but I
> > believe I've observed some EFs get reset after a successful
> > write/read.  Are you getting a valid response from the UPDATE BINARY
> > command?
> >
> My software doesn't give me any error. Unplugging and replugging the
> sim gives me good feedback: the test operator is still on the top of
> the plnm.
> > Unfortunately, I haven't found a reasonable workaround for this.  One
> > ugly hack that seemed to work with some SIMs on an HTC One V (a recent
> > Android phone ), is "priming" the SIM by first registering to the
> > network using a old Nokia 3310 or similar; the connected data is
> > stored on the SIM (EF.LOCI, I imagine?  I actually never figured out
> > why this worked.) and is good for a one-time use in the smartphone.
> >
> > Writable or custom SIMs are reasonably inexpensive, so for anything
> > over a handful of devices in a test network (with manual network
> > selection), that's probably the way to go..
> >
> I tried to used expired sims because I have loads of them... :)
> > Are you operating as MCC=001 MNC=01 (test network)?
> >
> Yes.
> > (Apologies to the list if this is the wrong venue for this.)
> >
> >
> > On Fri, Sep 7, 2012 at 8:15 AM, Dario Lombardo
> > < at> wrote:
> >> Hil list
> >> Today I've observed a strange behaviour when modifying the PNLM of
> >> some real networks expired sims (to be used with osmocom and openbts).
> >> I've put 001 01 on the top of the list. I've ejected and reinsterted
> >> the sim in the reader many times, and I'm sure that the value has been
> >> wrtitten.
> >> When trying to connect to my test operator I get the message "your sim
> >> card doesn't allow the connection to this network operator" from my
> >> android phone.
> >> Reading again the pnlm I see that the original list has been restored.
> >> This astonishes me... Is is possible that the SIM overwrites the list
> >> by itselt? Or is it the phone that does it? The android has an
> >> original, not branded, operating system.
> >> Thanks everybody for your help.
> >> Dario
> >>

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