What is a text message without a number like this?

Generally, this kind of text message without a number may be

Fraud SMS: Some criminals may send false SMS, pretend to be legitimate institutions (such as banks and government departments) and ask users for personal information and passwords or engage in other forms of fraud. These short messages are usually disguised and will not show the real sender number.

Please be careful when receiving such short messages to ensure your personal information and safety. In case of doubt, it is best to contact the relevant institutions for confirmation.

About SMS interception

SMS filtering function: Most smart phones provide SMS filtering function, which can add specific keywords or numbers to the blacklist to filter out illegal SMS messages. Open the SMS or message application in mobile phone settings, look for options such as "spam message filtering", "keyword filtering" and "blacklist", and add words or numbers related to fraudulent SMS messages that need to be blocked.