I can't get SMS when my mobile phone is turned off, but what is the reason for turning it on?

Whether the mobile phone can receive short messages is related to the communication company. As long as your mobile phone is in normal communication, you didn't receive the text message when it was turned off, because the communication company knew that your mobile phone was turned off. When your mobile phone is turned on, the communication company will tell you the short message sent to you before and forward it to your mobile phone. I think it should be!