The BT diversity - and a Binatone one - unless you download the manual or ask a brain cell (plural) there is no way to tell if the corded handset can dial on phoneline power alone.

As luck would have it I disconnected batteries and power and it works now. Albeit with an unusable LCD display.

The BT phone has loads of features like reading (copy in both directions) SIM cards. Being a GAP phone it will register other GAP phones of any make. And usually up to 5 or six for these kind of phones