Nokia Lumia 820 - I cannot send or receive text messages on my Lumia phone

  1. Check the signal bar at the top of the screen to ensure you have good network coverage. 
  2. Make a call from your phone to make sure that the network has registered the phone correctly.
  3. Go to Messaging > New (+) > tap 123 key located at the bottom left, type your own mobile phone number on the dial pad, type a message and then tap send. This will test your phone sending and receiving capabilities in one go.  
  4. Check the SMS centre number (Messaging > ... > settings > SMS centre number). Confirm it with your network operator.

If the previous steps do not help, insert a different operator SIM card into your phone to verify that the phone is working properly.