I think it depends on what kind-of headset you got, but if your headset can execute said function you:
1) Pair your bluetooth through wireless settings
2) Depress the directed button for operation
I have a Platronics BT and I hold the talk/hang-up button until it beeps back to me, let go of the button and then after it tells me to talk I give the command. Otherwise, I use simply press and immediately release that button to answer or hang-up on calls.