Using GT-I9100 in USA

Brian Kemp brian.kemp at
Wed Oct 2 14:23:57 UTC 2013

Hash: SHA256

On 10/02/2013 05:39 AM, Michael Spacefalcon wrote:
> Hello list,

Hello, responses inline.

> Following the recommendations I got here and my own gut feeling, I 
> have bought a Samsung GT-I9100 (Galaxy S2 international GSM
> version) with the hope of running Replicant on it.  (I saw the
> announcement that the S3 now works just as well, but the micro-SIM
> slot is a turn-off for me: all of the SIMs I have available for
> testing and experimentation are of the traditional mini-SIM form
> factor, and I have no desire to put them under an X-Acto knife.)

It's not an amazing solution, but you can swap a mini-SIM for a
micro-SIM for free, at least on AT&T. My wife did it when she went
from a Nexus S to a Nexus 4 (she has no interest in running Replicant,
but I get her old phone.)

> To the best of my understanding, the I9100 should be able to work
> in USA in 3 possible modes:
> * on AT&T GSM/EDGE; * on AT&T UMTS/WCDMA/3G; * on T-Mobile USA in
> GSM/2G/EDGE mode. (T-Mobile USA 3G/4G won't work because they need
> 1700 MHz uplink)
> The problem I'm having is that this I9100 (running whatever sw it
> came with, but I very much fear that the problem is in the
> baseband) seems to be consulting some psychic oracle to decide
> whether it should work or not.  There seems to be some kind of
> "coin toss" that occurs at boot time...  On some boot cycles the
> phone behaves just fine: sees my SIM card (tested both T-Mobile USA
> and Telestial), registers with the T-Mobile network in EDGE mode,
> and then works beautifully afterward: voice calls, SMS, data - was
> even able to watch a YouTube video over EDGE in this state!

Does your physical location change when you do this, or can you simply
repeat it no matter where you are? Wondering if two towers are
'fighting' for registration of your phone.

> But on other boot cycles (more often than not, in fact) some part
> of the sw stack (the modem, I'm afraid) gets into some kind of
> wedged state.  The visible symptoms are:
> * The phone spontaneously enters "flight mode", but in an erratic 
> manner.  If I as the user explicitly turn the flight mode on, an 
> airplane icon appears in the place of the cell coverage indicator. 
> But in this erratic state the no-coverage icon appears there 
> instead.  I only discovered that the phone is in some state such 
> that the AP software thinks it's in flight mode when I took a
> closer look at the menu that appears when I hold the power button
> down to power the phone off for reboot.  The spontaneous "flight
> mode on" state also shows up in the "Wireless and network" menu.
> * Once in that spontaneous pseudo-flight mode, the device does NOT 
> simply stay there "solid".  Instead it occasionally pops in and
> out of that state in a seemingly-random manner.  If I stare at the
> home screen, I can occasionally notice the no-coverage icon change
> to an icon with some bars, then back to no-coverage a split-second
> (or sometimes a full second) later.  If I do this idle watching
> while in the "Wireless and network" menu, I also see the "Flight
> mode" checkbox go on and off on its own, and the "Bluetooth
> settings" and "Mobile networks" menu items gets greyed out or
> restored in sync.
> * If I watch the "Status" screen under "About phone", I see a
> little bit more info.  When the icon at the top goes to no-coverage
> because of this pseudo-flight mode, the Status screen reports
> "Service state" as first "Out of service", then "Radio off".  The
> "Signal strength" shows "0 dBm 0 asu", which is obviously bogus -
> as if the modem is simply not reporting any valid values to the AP.
> The "My phone number" field usually stays at "Unknown" in this
> state, even though the SIM with the number in it is present all
> along.
> Needless to say, the device is not usable as a phone when it's in
> this strange wedged state - and it enters this state on every other
> boot cycle or so!  On some "wedged" boot cycles I have observed
> that poking at the device (for example, watching the "Wireless and
> network" menu screen, catching a moment when the "Mobile networks"
> submenu gets re-enabled, going into the latter, selecting "Network
> operators", then picking AT&T or T-Mobile) causes it to leave the
> wedged state and enter stable operation, as if it had a "happy"
> boot cycle.  But on other boot cycles the device remains wedged no
> matter what I do.  I also haven't done enough long-duration tests
> to see if the device ever enters the wedged state some hours after
> it had a "happy" boot...

There is something seriously wrong with this phone. I don't know if
it's the model, or if a modem firmware upgrade will solve it, but that
would be my first suggestion.

I wonder if it's trying to communicate on a frequency that the radio
doesn't support.

Install F-Droid and look for the "Network" application. You'll know
it's the right one when it says it's merely a wrapper for something
already in Android. Icon is white circle with black old land-line
phone handset in it.

You *may* be able to use those settings to force the radio to not do
stupid things - such as Preferred Network Type, etc. (My Nexus S lists
"WCDMA preferred" which I'm assuming is a default.)

It used to be that international versions worked best on T-Mobile, and
AT&T was the odd network out.

> The device is clearly not fit to be given to a non-technical end
> user (which was/is my end goal in all of this) when it behaves in
> this manner, and my spirits are low...
> Hence my question to this list: is there anyone here in this
> community who successfully uses (or has used) an I9100, or any
> other Replicant- supported GSM smartphone, anywhere in USA, on
> either AT&T or T-Mobile? If so, what has your experience been?  And
> if there isn't anyone in USA, what have other people's experiences
> been with I9100 in other countries?

> Here are the sw/fw versions my I9100 currently reports in the
> "About phone" menu:
> Model number: GT-I9100 Android version: 2.3.3 Baseband version:
> I9100XXKL1 Kernel version:
> se.infra at SEP-64 #2 Build number: GT-I9100-eng 2.3.3 GINGERBREAD
> XXKL1 test-keys

See if there's an update to that baseband...note that downgrading
basebands is generally difficult these days, so see my following

> I'm not sure how "pristine" or not this phone is: the ebay seller
> from whom I bought it listed it as new, but it came rooted: there
> is a "Superuser" app present.

Read the rooting instructions. If they look like something you'd be
able to do, factory reset it and flash stock firmware - the latest
version that is still vulnerable. Sometimes a vulnerable baseband is
part of the 'fun' required to get security broken so you can gets the

Start from a known "working" state. No clue what the instructions are
as I have not looked, but they might mean mucking with baseband.

> TIA for any clues, SF


> P.S. If someone can help me bring this I9100 into a state in which
> it works reliably on T-Mobile USA EDGE with T-Mobile USA SIM cards
> - by finding and flashing the right "magic" baseband version or
> whatever - I will gladly send that person $500 USD.  This is a
> serious offer, not a joke.  Offering cash bounties of this kind is
> my way of supporting Free Software - FOSS developers should be able
> to make money selling support for Free sw instead of proprietary
> sw.

- -- 
Brian Kemp

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