Why does the SMS sent by Apple's mobile phone show that it has been delivered?

Apple's mobile phone sends a text message indicating that it has been delivered, indicating that the receiver has successfully received it; Generally, there is a service reporting function in the SMS settings. When this function is turned on, the receiver will return a service report when receiving the short message. When the sender receives this report, it means that the receiver has successfully received it. Details are as follows:

1, Apple's mobile phone sends a text message indicating that it has been delivered, indicating that the recipient has successfully received it; But it can't show whether the other party has checked it, just a reminder that has been delivered. If the other party blacklists you, the SMS will be blacklisted automatically, and your information will not be displayed in the other party's SMS list unless the other party takes the initiative to cancel hacking you.

2. There will be a SMS center number in the setting of SMS function in the mobile phone. When sending a short message, the short message is actually sent to this short message center first, and then sent to the user at the specified number through it, which is equivalent to passing through a transit station dedicated to processing short message data. Sending only means that the short message has arrived at the short message center, and sending only means that the whole sending process of the short message is successful; But there is no feedback mechanism to show whether the other party has checked your number or blacklisted your number.