Send text messages between mobile phones to confirm whether the other party has received them?

Sending a report is to confirm that the other party has received it. Doesn't mean the other party has seen it. If the transmission is delayed, the reason is: 1. The other party is turned off. 2。 The network is a little slow. 3。 The other party's inbox has been bought, and you have to delete some information to receive it. 4。 The short message was saved in the system for 48 hours due to arrears of downtime. After 48 hours, you can't receive the message when you turn it on again. It's basically the top.