At the moment I made a direct connection of my phone to aux input , while for hand-free phone operation I already have BT connection, unluckily this one works only for phone calls, while for audio it does not, so I am waiting for another BT interface made ONLY for audio transfer, not for hands-free , just ordered on ebay. Of course for continuos operation it's better to connect to a 5 volts external power to avoid discharge of cell-phone battery.
The interface is something like this:
http://www.ebay.it/itm/350680756664?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649