No phone on Amundsen+

I have this week taken delivery of my 2nd hand 2015 Roomster, so am just getting to grips with the technology!

It has an Admundsen radio/GPS Navigation/Media system.  The cover of the manual says it is Admundsen+, but that is the only indication of the unit type. I can't find a menu option to give any information on the model or firmware.

I have been unable to get the "Phone" button to work.  Both the "Phone" button on the control head and on the left stalk of the steering column just turn the volume on/off.

I have reset the unit to factory defaults, but it is the same.  The manual does not mention the phone button turning sound on/.off and lists how to connect a phone.  But I can't get to the point of paiting.

Could anyone offer advice about what I should try please?

Thanks for reading.