How does Apple set SMS ringtones?

Download the SMS ringtone to be replaced.

Download itools and remember to upgrade the itools software to the latest version.

Itools installation

Install the itools software and ensure that it is updated to the latest version.

Open itools software

Open the itools software and double-click Media Management in the left column.

Select ringtones and import them.

Click Media Management, select the ringtone in the right column, click Import, and select the ringtone just downloaded to import into the mobile phone.

(Note that the Import button is located in the middle column of the itools window. )

Set SMS sound

Click Phone Settings-Voice-SMS Settings to set the ringtone as SMS ringtone. Remember not to ring too long.

Be sure to restart after setting the SMS ringtone!