by Takashi SASAKI (佐々木隆志)
Modern Android has seven volume settings, Voice Call, System, Notification, DTMF, Alarm and Ring. This flow shows current settings and allow you to choose each.
Older phones have less than seven settings. On these phones Voice Call and DTMF are identical. Ring, Notification and System are also identical. It depends on versions of Android and manufacturers.
If you have any question, contact me @TakashiSasaki on Twitter.