when I try to make a call

[steamerdave]

when I try to make a call "not registered on network" pops up and nothing else.
What have I done wrong or what setting did I screw up?

 

[Rukbat]

Do you have an account with a carrier? Do you have their SIM card in the phone?

If not, go out and buy service.

If yes, bring the phone to the carrier and ask them. It may be something they have to set differently in their computer.