The mobile phone number is empty, and the message is successful.

1. The other party may be using a smartphone.

I used some software to transfer your call ~ such as my mobile phone.

Set to call some people with an empty number.

Some people are on the phone.

Understand? It may also be the phone number of some enterprises.

Can only type

No score.

2. It is also possible that the other party uses a group sender (usually used to send spam messages), so it is impossible to call others back.

You may have dialed 1066.

Or 106. This kind of phone is SP's number, so you can't make a call.

If my answer can help you, I hope you can choose me as the best answer and wish you a happy life! ~