Why do mobile phones send text messages at the same time, some have delivery reminders, and some don't?

If the prompt was sent successfully, it must have been received. If there is no prompt, it may be because of signal problems, the other party's mobile phone is turned off and other reasons that it has not been sent to the other party's mobile phone. When the signal is good or the other party turns on the phone, you will receive a short message, and you will receive a report of successful transmission. If the other party's number is down or empty, it will prompt that sending failed, or display a red exclamation mark on the sent short message. Specifically, which SMS was sent successfully (Android phone or Apple phone, windowsphone phone phone), press and hold the SMS, and select View Report in the open window to see whether the sending status is successful.