Thanks Trevor.
Yes this looks as if it could be the answer. In the previous vehicle I used a Bluetooth transmitter tuned into a radio station for use with a separate android phone loaded only with music tracks & a Parrot Bluetooth module for taking voice calls on another phone. However you can only connect one phone at a time via Bluetooth to the X-Trails audio system & therefore that provides the facility for using only one phone at a time. So the gizmo you mention could be used for the android music phone, leaving the X-Trail's Bluetooth to handle voice calls..... I will check it out :-)