Why does the mobile phone number no longer exist, but the text message shows that the delivery failed?

Obviously, the mobile phone number does not exist, why does the SMS still show that the sending failed or the mobile phone number is empty? According to the query data, when the mobile phone of the recipient who sent the short message has an empty number, the short message will show that sending failed or waiting for receiving, and waiting for receiving will show the collection status. If you don't receive a text message after pushing, it is also empty.