What is a SIM failure?

It sounds like your sim card is bad. This means you need to contact your carrier for a new sim card. Before you do that try taking the sim card out and put it back in... sometimes it just gets moved slightly causing it to disconnect.

The SIM is what the phone uses to establish a connection with your cellular service provider for voice and data services.

If the SIM fails, the hpone is unable to communicate with anything on the cellular network. Get it replaced by your carrier if re-seating it doesn't fix the problem.