How long is the SMS setting valid?

The validity period of SMS refers to the time when the SMS you sent is stored in the SMS center!

When you send a message to a friend, your message is sent to the SMS center first, and then forwarded to your friend by the SMS center! The validity period you set is the storage time of the message in the SMS center. During this time, the SMS center will continue to send your message to your friend's number until the other party receives this message!

For example, when your validity period is set to 24 hours, send a message to a friend, just as the other party shuts down. As long as your message is turned on at any time within 24 hours after it is sent, you can receive your message. If the other party doesn't turn on the phone within 24 hours, the other party won't receive your message!