Recently I am working on a SMS notification function. The interface parameters are all written according to the document, but SMS cannot be sent. After checking for a long time, turned out to be that the content of the text message contained spaces . The English punctuation marks used in the previous text messages had a space after the symbols, and date('Y-m-d H,i,s' was used ) function, and then after deleting all the spaces in the text message content, the message was sent successfully. It stands to reason that the text message content can have spaces, and it may be the text message content restricted by the SMS gateway platform.