My boyfriend received a text message. The number was empty, but it was mine before. What happened?

There may be a system error. The information sent before was saved on the server, but it was sent later because of delay or other reasons.

It could be a number changer. I remember there seems to be a software on the internet that can block your mobile phone number and use a custom number.

Of course, you can think it is haunted, but this is obviously not true.