
The connection icon is always displayed on my iPhone or iPod touch
To support two-way communication between your computer and your iPhone or iPod touch, Signal leaves up a persistent connection and this is why the connection icon is always displayed. The benefit to this is that whenever something changes on your computer's media player it will be displayed on your iPhone almost immediately.
Note that this doesn’t prevent the iPhone or iPod from entering sleep mode and doesn’t consume any additional power while in sleep (the connection is closed and re-opened when the device wakes).