How to make Bluetooth headset automatically set to primary sound device

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http://askubuntu.com – When I turn on a bluetooth headset paired with my phone, it automatically sets the headset as the primary sound output device so that calls/music play through the headset without me having to manually configure anything. How do I do this in Ubuntu 12? I can pair a headset easily with the bluetooth applet, but whenever I turn on the headset, I have to manually open the sound control panel and select the device every time I want to use it, which is immensely frustrating and huge waste of time. Like most headsets, if it's on, it's wasting battery, so the user probably wants to use it. (HowTos)