If your device isn't working properly, you can try several solutions to solve the problem.
In most cases you can solve the problem by following these guidelines:

If your SIM card is faulty, this is displayed.

Solution: Check if your SIM card is faulty by inserting it in another tablet. If your SIM card is not accepted by the other mobile phone, your SIM card is probably faulty. Log on to Swisscom Customer Centre to order a new SIM card.