The status of SMS sent to E52 will be stored.

Is the information capacity of your mobile phone almost full?

Resulting in a state of being stored all the time.

I suggest cleaning up your information.

Then try again.

If not.

Call 10086.

Manual business

Ask them to help you reactivate the SMS function.

And you can change your mobile phone card to another mobile phone.

I am texting E52 to see if this will happen again.