Some short messages sent in groups show delivery, others don't show delivery, and they don't show delivery. Did the other party receive it?

There are the following possibilities: First, the receiving time of the other party's mobile phone is short, and the validity period is 1 day. If the other party's mobile phone is turned off or out of service area, and there is no signal during this period, you can't receive SMS. Second, the network transmission failed. Your mobile phone has no receipt report, so you can't see whether the short message was sent successfully. Third, some mobile phones failed to send, but the prompt was successful. For example, my mobile phone can send text messages to fixed telephones. Although it was not successful, the mobile phone showed that the short message had been sent successfully.