It certainly seems that the Aastra 6739i is the new king-of-the-hill with respect to feature-laden enterprise class SIP desk phones. Amongst it’s myriad features you will find included the ability to use a Bluetooth headset .
For the past nine months I’ve used the Savi Go Bluetooth headset around the office. In that case I’m using the headset with a soft phone since the Savi Go is provided with a class 1 Bluetooth USB dongle. The Savi Go is kinda unique because it supports wideband audio over Bluetooth.