hi freind;s i;m facing the same problem !! i use n900 and is working fine more then 2 mounth now the signal is going and coming i did put some papaer and every thing is working for some times and the signal is gone and the sim card logo with the red line appers
i try to update the phone still the same problem !! an body know the sorce ? if is a electrical problem tell me where to look is is software can you explain how to fix it !! thank you

same here i start testing the paper solution and give it a try looks like nokia buildt in a self destruction module into n900 ;-)

so far so good the paper solution works fine no more sim card trouble

N900 is very sensitive when it comes to SIM. try a new SIM card, IT WORKED FOR ME. old SIM works on other phones but on N900 it does NOT.

I've had this error three or four times over the two years that I've had my N900, and on all occasions, it's been fixed without changing either the phone or the SIM.

For me, the problem happens when I'm trying to do too much in the way of overclocking / undervolting. I didn't make the connection the first time and reflashed the whole phone. Some months later, it happened again whilst I was playing with higher CPU speeds; I went back to slightly more conservative settings (250-900) and the problem went away.

Recently (many months after the above, same hardware), I started playing with 250-1100, with SmartReflex on VDD2 only... it seemed stable. But, a few hours of that, and some use of the memory card, the SIM dropped out. I reverted to my previous settings, and it reverted to working flawlessly.

I haven't isolated the problem further yet; perhaps I could sustain 1100MHz with more voltage and no SmartReflex, but I'm not sure that I intend to try. The observed evidence from two years with the same device is that my particular N900 is happy and stable at 250-900 with SmartReflex on VDD1 and VDD2, and that pushing it further than that works for a few hours, but is not stable.

Your mileage may vary; some people will have a loose or malunctioning SIM card, an unlucky few will have a broken phone, but I've reproduced the problem enough to be fairly sure that in my case, this is the cause.

I faced similar issue after reflashing. But i re flashed with firmware file from some other region . To be specific I'm from India instead of installing region specific firmware [http://tablets-dev.nokia.com/nokia_N900.php Firmware Download] i installed global firmware. So after reflashing sim is not detected again reflashing with region specific firmware fixed the issue. Hope it helps to some one. :-)

i'm 99% sure this is motherboard problem,
1. try different firmware - was ok for several weeks
2. paper solution another several
3 no other solutions
i sent my n900 to nokia. i still have warranty on it. this is repair report....
Repair Description
- VID
- Screening
- Replacement- BATTERY COVER ASSY
- Replacement- A-COVER FRAMING
- Replacement- LCD AM 800x480 LTPS CO Caucasus
- Replacement- SCREW M1.4x2.8 BLACK CAMERA-CROSS 360 SP
- Replacement- SLIDE FLEX ASSY (I0101 - I0102)
- Replacement- TOUCH WINDOW ASSY (I0003 - I0005)
- Replacement- A-COVER ASSY
- Unit exchange
- Adjustment
- Software update



History of Job
05-10-2012 - 13:00 - Packed ready to be sent
05-10-2012 - 10:39 - Repair completed
05-10-2012 - 10:12 - Final Inspection awaited
05-10-2012 - 08:27 - Full test awaited
01-10-2012 - 14:37 Awaiting quality control validation
01-10-2012 - 14:31 Received back from higher level repair
19-09-2012 - 06:35 Sent for higher level repair
18-09-2012 - 10:07 Escalation to higher level repair awaited
18-09-2012 - 09:31 Awaiting Inspection
18-09-2012 - 08:02 Repair in progress with technician
14-09-2012 - 10:02 Software upgrade awaited
14-09-2012 - 09:06 Repair in progress with technician
14-09-2012 - 09:06 Repair started
12-09-2012 - 03:59 Screening awaited
09-09-2012 - 15:30 Receipt awaited
08-09-2012 - 10:15 Repair booked

After few months my N900 still have the same sim problem.

I tried a lot of things, but it still in problem.

1) I tried to clean the connectors.
2) I changed the sim card.
3) I tried the "hammer and nail" way. It's was functionnal for few weeks, but now it's still broken.
4) I tried to format it. Same thing

Now I'm very sad. I've this phone since 4 years and I love it, but I think it's the end.

Thanks to everybody who's trying too help.

http://talk.maemo.org/showpost.php?p...1&postcount=18

This works to get Sim 'online' again

Hi all,
I have the same issue with my beloved N900. I manage to keep it running with a thick piece of paper between the SIM and the battery. but the whole thing seems to be a bit sensitive. If the phone case is squeezed a bit, e.g. while being in the pocket, it loses the SIM card connection, and without any warning. Very annoying.

My phone is still under warranty, so I could send it in to Nokia, but I've read that usually they cannot repair this (motherboard exchange necessary), so they scrap it and provide a replacement, usually a N7 or N8. Bad deal!

Has anybody tried out the above solution? I feel unconfortable doing it.

Cheers