I sent a message to my father. Why didn't he receive it?

If only one or two items are not received, it is not a problem. It may be that the network is unstable and the information is blocked in communication, resulting in the loss of information. If you don't receive all the information, it may be that the information is set incorrectly. See if you have set the number of the information center and blacklist you. Generally, that's it!