Is it successful to display 1 after sending SMS?

No, SMS can set whether the SMS was sent successfully or not, and there will be a receipt SMS function.

Apple phone settings:

1. Open Settings.

2. Click on "Information"

3. Find "Send Read Receipt" and enable this function.

4. After setting, you can know whether the short message sent has been received by the other party. If it is not received by the other party, the background of the short message box is green.

Android phone settings:

1. Open SMS settings.

2. Click Advanced

3. Open the delivery report.