The weather's been so lovely in Seattle this summer that I've been driving the 911 to work quite a bit. I am loving the Bluetooth enabled head-unit I have in Vlad (my '87 BMW 535is) both for hand's free phone use, and for streaming audio.
Ages ago I put a 3.5mm audio plug in the Porsche connected to aux out of the pre-Bluetooth head unit. But this was clunkly and I couldn't do hand's free phone.
I decided to try one of the inexpensive Bluetooth units you can buy now. I picked this up on Amazon for $39.99 figuring it would be worth a try.
Kinivo BTC450 Bluetooth Hands-Free Car Kit for Cars with Aux Input Jack (3.5 mm) - supports aptX
Installation is a bit of a hack job, but the nice thing is that it's all easily removable for when I show the car.
I used the included double-sided sticky to attach the control/mic unit to the steering column. It's relatively easy to reach while driving and is nice and out of the way.
The unit plugs into a cig lighter outlet and while I hate having something like this mar the look of the dash, it's not too bad, and as I said above, easily removable. The wire to the control/mic unit is stuffed between the knee-kick panel and the dash and the 3.5mm cored to the aux input snakes thorugh the lock hole the glove box.
As I use it more I'll report on how well it performs for hand's free phone use. For audio streamed from the phone it's excellent.