How do I make a Google Voice call from my cell phone and keep my cell phone number private?

I have a Google Voice phone number and account. I only give out the Google Voice phone number. But if I return a call with my cell phone while I'm not at my computer, how do I keep the actual cell phone number private and only display the Google Voice phone number on the other person's phone?|||You need to dial using Google Voice app. Only then will your Google Voice number shows instead of your cell number.