OK. Time to clear this sim swap mistery. A few days ago i dropped the n900 on the concrete and some parts wouldn't work anymore so i had to open the phone to repair it and decided to test the sim swap.
Sorry no camera at hand to take pictures
So i soldered some wires from the sim slot of n900 to a sim slot of a nokia 3310.
1 Started the phone with a vodafone sim card - ok
2 Put the phone in offline mode, remove tyhe vodafone card and insert an orange sim card
3 Put the phone back in normal mode - a message pop up on the screen displaying "GSM: orange", but on the operator logo on the screen the text was still showing vodafone, but i could call and be called on the orange sim.
4 Decided to remove the sim without puting the phone in offline mode - It worked! in a few seconds after the sim is changed a message popped showing the network of the sim i puted on. however the operator logo was still showing vodafone, no matter the operator sim, but that is not a big deal since the phone is on the network of the inserted sim
5 Started up the phone without a sim card, and inserted the sim after, in this case i could not get the phone to acces sim
6 i decided to do mmore, since it is a gap of a few seconds from when you remove the sim and the phone realising it has no sim, i wanted to check something:
i removed the sim card during a phone call and guess what? The phone call continued without the sim!!! i couldn't belive it. My first thought were wow i fond a vulnerability to make free phone calls!!!
Unfortunately it didn't worked that way: I put a cosmote sim on n900 and called miself on the orange sim. Before answering i removed the cosmote sim form n900 and answered. it worked, but when i check the credit on cosmote i saw i was chrged, even if cosmote sim was no longer in the phone when i answered.
However the conclusion is that sim swap is possible and very easy, you don't even have to tur gsm off when changing the sims. The only "problem" is that the operator logo of the sim you started up the phone remains there, no matter the sim. ( ithink that can be fixed by refreshing the hildon desktop, but i didn't bothered to do that).
About the drop that make me open the phone, it was a nasty one. The battery jumped out of the phone almost a meter away and the back cover received a crack under the solar panel(but thanks to it is not visible).
My first thought were that the gsm chip or emmc got damaged by mechanical shock, but to my surprise, the worked, bluetooth and wifi also worked. I thought everything was ok. But later on i discovered that flashlight wouldn't work anymore, neither the main camera, neither the secondary camera and as a bonus gps was also dead.
The gps repair was easy all i had to do was to heat with hot air the gps chip for a few second, and the gps was back to life.
The main camera simply showed a black screen, the secondary cam (using the mirror app) showed something like "gstreamer error", and flashlight app was dead. All this problems camed from the main camera module that got some internal damage from the shock. The solution was changing the main camera module.
I always saw that nokia n97 takes silghtly bettet pictures than n900, and in every review i saw on the internet when comparing the camera of n900 vs 97, the n97 wins.
So i had an n97 lying around and decided to put its camera module on the n900.
At first sight you will think they are very different, since the n97 camera module has a ribbon cable that connect to the motherboard, and the n900 module has just some pins.
But if you peel off that ribbon cable of n97 cam module, you'll discover the same pins. So i did, placed the n97 cam in n900 and it worked!
My n900 now takes better pictures than before with the new module. Also the flashlight and secondary camera went back to life after module replacement.
With this setup i wanted to do more, so i opened my nokia n86 in the hope i will be able to do the same and to have an 8mpx camera on n900. Unfortunately the n86 cam module is way bigger than n900/n97 cam module so it wouldn't fit in there .
However i should have tested if the pins are the same, maybe with some wires soldered it would work but that will be tested next time .