Here's the problem, your CIR is what you are guaranteed, anything beyond that you may or may not get. Burstable limits are also limited to time as well. You usually can't burst for an unlimited time.
I personally would not base any of my voice call traffic shaping on what you could potentially have versus what you are guaranteed. The last thing you need is to have an important voice call dropped or voice quality compromised. Data may not be as big a deal.
Video requires QoS as well for smooth looking images so the same thing applies. Good luck.