I’ve also just tried to clarify the law on actually touching a mobile phone when mounted and it basically isn’t stipulated in the law so I’ve had to find an official police interpretation and I’ve found this
‘Pushing buttons/touching a phone while it’s mounted in a cradle or mounted on the steering wheel or handlebars of a motorbike for example is not covered by the offence (previously partially quoted in my last post above)
Provided you don’t hold the phone it is, in our (the police’s)opinion, if the device can allow for hands free calls, it would be legal but inadvisable to use whilst driving, however it would ultimately be up to a court to decide