WARNING – Bluetooth on the RPi can be a nightmare and result in massive time loss!  If it just works for you then great (and consider sharing how). If it doesn't and after hitting your head against a wall for hour after hour it still doesn't it isn't just you (search online RPi forums for 'bluetooth' to get a feel for the number of issues people have).  We found massive problems getting a simple USB Bluetooth serial (rfcomm) link to work properly and ended up abandoning it after huge amounts of time lost to trying to troubleshoot it…

From the command line enter:

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install bluetooth bluez-utils blueman

List the connected USB devices

lsusb

Find the Bluetooth adaptor, e.g.
Bus 001 Device 006: ID 0b05:17cb ASUSTek Computer, Inc.

Copy the ID without colon and write it into the /sys/bus/usb/drivers/btusb/new_id by adjusting and using the following command:

    echo "0b05 17cb" >> /sys/bus/usb/drivers/btusb/new_id

Now use the following command to load it:

modprobe -v btusb

Now use the following command to edit the config:

nano /etc/default/bluetooth

Copy these lines into it or update what is there as needed:

Press CTRL+X to exit and select ‘Y’ to save

HID2HCI_ENABLED=0
HID2HCI_UNDO=0
HIDD_ENABLED=1

Restart Bluetooth:

sudo invoke-rc.d bluetooth restart

Bluetooth failed to work after this within the RPi GUI for us. This was the command line solution:

sudo nano /etc/group

move to the line:     lp:x:7:
Change it to be:     lp:x:7:pi

CTRL+X to exit, selecting ‘Y’ to save and then reboot