What should I do if Xiaomi 5x SMS can't be sent out?

Xiaomi 5X SMS can't be sent out because there is a loophole in the mobile phone system, which can be solved by upgrading the system.

Taking Xiaomi 5X mobile phone as an example, the specific operation includes the following steps:

First, open "Settings" on the phone desktop, as shown in the figure below.

Second, open "Settings" and find the "My Device" column, as shown in the following figure.

3. Then click the "MIUI Version" option to proceed to the next step.

4. Find the "Settings" option in the upper right corner and click to enter the next setting.

5. Click the option "Download the latest complete software package" and wait for the system upgrade to complete.