You can't sync contacts with a headset device that is connected through Bluetooth device. In the most fortunate case, you can call back the last called through the button available on the headset. If you check the official website where the specs are posted, you'll see that it lacks the feature you've mentioned in your question.
Here is the website: http://www.plantronics.com/us/product/voyager-legend#fndtn-specs
As far as I know, Bluetooth headsets don't offer the possibility to sync contacts.