Apple 1 1 sent a text message indicating that the delivery failed, but how did the other party receive three?

When the signal is bad, sometimes the message is sent out, and the mobile phone doesn't receive the receipt sent by the operator, so it will think that the short message has failed and try to send it again, but the short message may have been sent out, or when the operator's base station sends the information to the other mobile phone, because the signal is bad, the message fed back by the other mobile phone to the base station has not been received, and the base station will try to send it again.

This is true of any type of mobile phone, and it will be encountered by iphone, Android or smart non-smart phones. It seems that I have never encountered repeated deduction.