Possible cause 2 of 9:
Your SIM is faulty
If your SIM is faulty, this is displayed.
What you need to do
Check if your SIM is faulty by inserting it in another mobile phone. If your SIM is not accepted by the other mobile phone, your SIM is probably faulty. Find a SingTel dealer near you using our Store Locator to order a new SIM.
Did this solve the problem?