It was first seen last year but finally, the Nokia DAB headset add-on has hit the shelves, but only for a select bunch of handsets.It's a simple and quite attractive proposition for lovers of the likes of Planet Rock, 6 Music, One Extra, Radio 7 or any of the 24 national and 50 local stations available, converting your phone into a mobile digital radio by simply plugging the the headset into the handset. Once you've done that, just flick through the stations listed, choose your favourite and you are away. Well, some of you are.You'll need a smartphone that uses Nokia's USB On the Go functionality, which is currently the Nokia N8, C7, C6-01, and Nokia E7. Not many handsets, but one more than when it was first seen, so there's hope yet. If you do have one of those phones, it's the DAB headset isn't bad value at £45 from any Nokia shop. It's free if you buy an N8 online - but we suspect the 'free' element is overshadowed somewhat by the price of a sim-free N8 smartphone.