If you want something portable, my wife has this little guy
http://www.amazon.com/BlueAnt-Handsfree-Speakerphone-Bluetooth-Packaging/dp/B006O1NKT2/ref=sr_1_10?s=wireless&ie=UTF8&qid=1387419380&sr=1-10&keywords=blueant
It's pretty awesome. Clip it to the sun visor and go. Totally hands free...