To set an MP3 file for use as custom ringtone system-wide, do the following:
1.Copy the MP3 files to your phone.
2.Go to Settings > Sound > Device ringtone.
3.Tap the Add button to launch the media manager app.
4.You will see a list of music files stored on your phone.
5.Your selected MP3 track will now be your custom ringtone.
You can check the full specs here: 10.or D
Praveen kumar raparthi