How to Make Phone Calls from Mac Using iPhone - OSX Daily | Mobile Technology |

"If you have a Mac and an iPhone, you can now make phone calls from your Mac using that iPhone. The phone call will sound through the Mac speakers and use the Mac microphone, but the actual call itself routes through the iPhone. This is a part of the Continuity suite, which is really nice feature set in newer versions of iOS and Mac OS X that allow for seamless transition between Macs and iPhones and iPads. Phone calling from the Mac is quite simple to use once you have it set up properly."

Via John Evans