How it's possible to use a bluetooth dongle with a verdex?

I have a verdex XM4 BT, it's not avalable with the uart interface in place ?

I must load an other module ? Hci_usb ?

I believe you can. you would load hci_usb (if it isn't automatic)

the advantage of using usb is you can use an off-the-shelf part and you can use an EDR adapter at the full 3Mb. and, of course, you can use it for audio which I think the internal bt can't do still.

I don't have a verdex to try but I believe even a bluegiga could be connected over usb with a regulator thrown in... see

btw, lots going on in the next few kernel revs:

* a patch was just accepted to regulate the packet flow for sco will bring headset audio quality up to the minimum standard

* the main limitation of using usb instead of a uart is being worked on now on bluez-devel: allowing multiple simultaneous headset (sco) connections.

* we also have some patches floating around for using esco for better quality.