Sounds like im not the only one with this problem.

I use Saunalahti / Elisa in Finland; latest firmware. The timeout thing did cross my mind since people trying to call me get the "person you are dialing could not be reached" thing, the same they would get if the phone were off. Then the first time this happened I started getting angry people calling my friends trying to reach me after I made a phone call just 2 hours ago, so the phone died some time within the two hours, so its not like the the phone has been sitting idle for ages. And to the best of my knowledge my phone tries my email server every 10 minutes...

I really know very little about gsm networking. Maybe there is some inherent process in all mobile phones that pings the network every x minutes telling it that its still there, and maybe this process somehow miraculously dies on the n900 occasionally.

Its odd cause Ive used this phone for >4 months and the first time this happened at all was about a month ago. Could be some buggy app (yes I have extras-testing enabled) but cant recall anything that should be directly related to gsm.

When the next firmware comes out Ill just dump half of the apps I dont use anyway, maybe that will help.