Why do you receive different blank messages?

The above numbers are sent by people who know you (he may be a small official in an enterprise, and he has registered many employees' mobile phone 139 mailboxes, and the passwords are all set by him). Send you short messages with different registered mobile phones without content, the purpose is to harass you and give you a bad mood! You can think about which of your friends is the small manager or boss of the department. Just look it up.