Apple 1 1 can't send a short message. Hasn't it arrived yet?

What is the reason why Apple SMS has not been delivered?

1. The signal in the area where Apple's mobile phone is located is not good. You can't send text messages without a signal. Send text messages to places with good signals.

2, the mobile phone number is in arrears, texting costs money, and the user's mobile phone number is in arrears. In this case, SMS cannot be sent.

3. Just turn on the phone and turn it off.

4. The user is blacklisted by the other party.

5. The other party's mobile phone has no signal and is in shutdown or flight mode.