Why can't Unicom King Card send text messages?

If the mobile phone can't send short messages, troubleshooting can be carried out according to the following conditions:

In case 1, the number of the short message center is set incorrectly. Please reset the correct number of the SMS center.

In case 2, if there is no signal or the signal is poor, you can go to a place with strong signal to test.

In case 3, the short message sending function is turned off, so you can turn on the short message function and try again.

Case 4 is blacklisted by SMS and can only be used normally after being blacklisted.

In case 5, the number balance is insufficient, so you can pay and try again.

Situation 6: There is something wrong with the mobile phone, so you can change the machine for testing.