I’m using ubuntu 10.04 (lucid lynx) with usb bluetooth dongle (generic)
Open up your Ubuntu Software Center then type bluetooth from the search box. Select Bluetooth Manager and then click Install. It will install all the necessary required dependencies and also support for the A2DP.
Alternatively you can install Bluetooth Manager via terminal.
$ sudo apt-get install blueman (enter your password when prompted)
Once your Bluetooth Manager is installed. You’ll see the bluetooth icon probably in your notification area. If Icon does not appear It may required your PC to restart or logout/login to enable, but make sure your usb bluetooth dongle is inserted and detected properly from the usb port.
Click the bluetooth icon and setup new device then follow the instructions in pairing a device. If prompted for password key, enter 0000 it’s written in your Nokia BH-503 Manual.
Now, If everything works accordingly then the device will be paired. You’ll see your bluetooth headset device, Nokia BH-503 being detected. Right-click and select Audio Sink.
Next step, go to System -> Preferences -> Sound. Select Hardware tab and you should see it’s included. Click the Profile option and select “High Fidelity Playback (A2DP)”.
Lastly, click the Output tab and choose your output sound device.
You can now open-up your favourite media/music player and hear the music in your Nokia BH-503 Bluetooth Headset.