I've had my P800 for just over a month. I have noticed that once or twice a week the phone seems to think that there is no SIM card installed. When this happens the phone suddenly displays a message "Insert SIM card" and goes into a waiting mode, expecting some kind of input/password.
The only way to get the phone working again is to power it off and power it on again. Very annoying.
P800..forgets SIM card
hmmm. that shoudn't happen 😮 I'm sorry to say, but, you might have a lemon there. :cry: If your P800 is with warranty, I suggest you go for an exchange or have it taken looked at.
Wishing your P800 speedy recovery.
clean the sim contacts. It happens regularly on my Nokia phones (not on the P800).
It sounds like a problematic connection with the SIM.
I agree with oferlaor, clean the sim contacts, especially on your card -- I had the same problem with my phone on the first day, wipped out the SIM and polished it and all has been fine since.