Firefox OS lets you control the sounds on your phone. Learn how to change your alerts or ringtones, add your favorite song to your ringtone library, or turn your phone on vibrate or silent mode.
Here's how to add new ringtones if you don't like the ones that come with your phone:
Got a ringtone that's too good to keep to yourself? Share it with other devices!
Quickly silence your phone in a meeting or at a movie theater.
Make your phone vibrate when you receive a call.
While you can use the volume buttons to quickly make your sounds louder or softer, you also have the option to set different volumes for different functions:
Just to report the lack of the image in the third step of the "Adjust the volume on your phone" paragraph: The image "volume slider" does not exist.
Thanks for reporting this. I've re-uploaded the image and named it the same ("volume slider").
That was 45 minutes ago and it's still not showing up in the article. I'll file a bug if it's not fixed in another hour.