I have a computer and Android phone connected by WiFi. I want to use my computer to make calls through the phone. Is there any way to do this?
Remote Phone Call (Click Here to View App on Play Store) might help you with the GSM Calling via WIFI & BLUETOOTH.
Google VOICE & HANGOUT (Default app on android Phone) for PC you need plugin for installing HANGOUT..
There is a startup in YCombinator's incubation center that is currently solving this very problem, they are called PushBullet.
Unfortunately though, their app is still a chrome extension, and it does not allow you to directly make calls from PC, your phone is connected with PC over LAN (read wifi), and it binds a port from your phone to the PC and allows you to add one more layer of abstraction between your phone and PC
Try Sidesync 3.0 from Google app store.