To play and pause your music, press the center button once (x1). To skip to the next track, quickly press the center button twice (x2 fast). To raise the volume, press the plus symbol (+). To lower the volume, press the minus symbol (-). See illustration below for further details.
Simply push the center button once (x1) to answer the incoming call. To hang up the call, just push that same center button again (x1). To raise the volume on a call, press the plus button (+) and to lower the volume, push the minus button (-). For further details, see the image below.