Here's how you can bypass the iPhone's lock screen to control music tracks or volume.
1. Go to the iPhone lock screen.
2. Press the Home button twice.
3. You'll see the following: Name of music track The volume control The back, forward, and pause buttons
You can also control the volume via the plus or minus buttons on the iPhone 5 headphones.
For more, see the original article at the link below.
Four time-saving iPhone tips | CNet