I got a Sharp GX10 from a mate. It was locked to Vodafone so he rang up to find out how to unlock it. I did the following.

Put in a Vodafone Sim Card.
Turned phone on and entered pin.
dialed *01763*6371#
went into settings -> security -> mep locks
Entered the Handset Code
Went into Network -> Deactivate
Entered the 12 digit number and it said DONE

I then put in my O2 Simcard. It asked for my PIN then asked for the Handset code. I entered both numbers and the phone came on. It has on the front of the screen "Emergency only" and I can't call anyone and I don't think anyone can call me. I can access my phone book, inbox, etc. though.

Any idea what is wrong?

Cheers.

I fixed this problem by letting the phone automatically detect my network.