Note: This app is not an official SONOS app.
SONOMOTE is solely a volume controller app for SONOS. Why another app which only controls volume when SONOS already have an app? Well, this app:
1) Starts up very fast, reducing time until you can adjust volume from your phone.
2) Controls volume on all SONOS devices or zones from a single view, reducing time spent navigating to a specific room.
3) Can control the volume of a specific device even from your locked iPhone and/or by adjusting your phone volume buttons (!), allowing your phone to control SONOS volume without unlocking your phone and starting an app.
All in all, this makes adjusting volume on your SONOS devices very fast.
Note: This app requires uPNP is enabled and allowed on your wifi network / router (usually enabled by default), and no traffic is blocked between your iOS device on the network and the Sonos devices. Note also that the skip song controls on the lock screen is used to move between Sonos devices/zones and NOT to skip songs.