Iphone not reading sim card

i got the same problem once in a while. what i do is to simply turn it off and then turn it back on again. if it doesnt work, i just do the whole off-on thing again, with a few minutes interval.i know its not really helpful, but it works for me.

hold the Home button and power button for 15 seconds .. after 10 seconds you will relize that the icon to turn the iphone off appears.. ignore that .. and after 5 more seconds it will turn off by itself... then ait about 20 seconds.. and turn it back on ..

if that doesnt work maybe its your sim card or... <edited by host>

this might be tricky .. but .. try deleting your current firmware.. and download another 1 ...

< Edited by Host >

If your iPhone is under warranty then you should have no problem seeking assistance at an Apple store.... but before you do, and I don't know if with SIM problems you still have access to standard menus but on the assumption that you do: try opening Settings, hit General and scroll down to Reset and then do a Reset Network Settings. Often a good place to cure intermittent network issues and maybe you are experiencing something along these lines.

I have the same problem!
I updated my iPhone to OS3.1 without a functional sim-card.
I can't activate the iPhone and it isn't visible in iTunes..