If you own an Apple iPad with 3G/4G capabilities you will be constantly be warned that there is No Sim Card installed if there is no sim card present and you are only using Wifi.  To stop these warnings please follow these steps:

  1. Click on the settings button
  2. Toggle Aeroplane Mode to on
  3. Connect to Wifi

Your iPad will still browse the internet, download email etc.. normally but you won’t be prompted by the No Sim Card warning at random intervals.