I got a new Dutch SIM last night, but it won't work with my unlocked iPhone 3G.
It simply says 'No signal' in the top left corner.
I've tried 3 things.
A restore. It didn't make a difference and I get a message telling me the SIM is invalid when I connect it to iTunes. And the message in the top left switches from 'No signal' to 'Invalid SIM'
A reset. Settings/General/Reset. No difference.
Varitaions on switching Flight Mode on/off.
The SIM works and the iPhone is unlocked.
The SIM works because I tried it with an old donkey of a Nokia I have and I could make calls.
The iPhone is unlocked because I'm able to use it with my Irish Prepaid SIM, which is not the original SIM.
These are the only 3 things I can find so far