Ive phoned t-mobile and had myself removed from the signal sharing service with orange

still no fix, any ideas anyone? lol

I'm not so sure if is a carrier issue, got my sim card in my old n95 and it works fine.

I think i need to try another sim card in the n900 to see if the issue is with the phone.

At this point I do suspect some program i installed may have corrupted something....

Might try to reflash it at the weekend to see if it makes a diference.

i was under the impression that nokia no longer fixed n900's as is cheaper to give customers a new unit... at least that was my understanding for broken usb's....

Well it's due back next week, and if they do waste 3 weeks just to exchange it then I'm not gonna be impressed.

It probably depends on which country you're in if they fix or replace them.

Tried briefly with a virgin mobile sim card and it worked fine (virgin mobile uses t-mobile carrier).

Replaced with my sim and status keeps swapping from displaying the carrier and no sim sign....

maybe is just a problem with the sim card metal contacts...

Well, I have a similar problem in SF Bay Area with T-Mobile.
It doesn't give me any message but phone communication (3G + voice)
disappears, while WiFi and BT is active.

All things point to new hi-speed T-Mobile 3G+, it was introduced in SF Bay Area last week.

Have you guys managed to resolve this problem?

It seems that in the UK, Nokia repair centers can repair n900 free of charge if they less then 2 years old.

So you've already read about the issue with the leaked PR1.2

I had the same thing happen to me. My N900 is an alarm clock now with poor battery life (I imagine the battery needs replacing).

Just ditch it and get an N8 or E7 and cross your fingers that this whole QT thing and the upcoming changes to symbian will make the symbian OS more user friendly.

As soon as I updated to the most recent firmware on my n900 my device started slowly failing to maintain 3g on tmobile until i finally got the sim card symbol with the red line through it and the notice that all telephony functions have been disabled.
I decided after trying many things that it was bad soldering between the sim card reader and the mainboard and I just gave up and bought an N8.
Boy am I happy with the N8 hardware and the extras like wifi N and 5band 3g and gorilla glass and dolby surround sound this is a nice phone but I'd prefer a hard keyboard so I'm seriously considering buying the E7.

Browser on N8 sucks balls like seriously. I can't wait for the next symbian update. They've been releasing minor OTA updates recently for N8 instead of one big update like with N900 so that's also nice.
N8 processor is slightly slower than I'd like. I'd like to see a 10 to 30% increase in speed. Since symbian is open source now I'm hoping we can overclock it.
Another stupid thing about N8 is the "message deleted" popup totally covers the subject and sender fields of your next email that you are reading so you have to wait for 5 seconds until it disappears and apps will once in a while just suddenly close on you or move to background.

Just has to return 2 N900,s to nokia for free repair because of all telephony functions are disabled due to a communication error