DockPhone lets you make calls right from your Mac. With this app, you can speak freely via the microphone of your computer.
To start a call, you need to type or speak any number or a name. DockPhone lets you search in your contacts, or dial arbitrary phone numbers. Hit the Dial button and enjoy your phone call.
This app requires to have both iOS 8.1 on your iPhone and OS X Yosemite (10.10) on your Mac.