How does Apple 5s check whether the SMS has been sent successfully?

How to check whether the SMS was sent successfully through iPhone;

1. First, turn on the phone and find the text message.

2. Click the icon in the upper right corner.

3. Select the recipient.

4. Edit the message content.

5. Click Send.

6. If the transmission is successful, the mobile phone will ring the sound of sending SMS, as shown in the figure, and the transmission is successful. If it is not successful, you will be prompted that sending failed.