I have an unusual, at least in the UK, Panasonic KX-TGH260 DECT wireless phone system with three wireless handsets. The base station doesn't connect to a landline but connects to my Pixel 4a by Bluetooth. There is no special app on the phone, it is just paired as usual with the base station. All the the DECT phones can make and receive calls and give notification of incoming texts. It seems this capability is standard on Android Bluetooth implementations so theoretically I would have thought a tablet could connect to the phone by Bluetooth and do what my base station does - but I have no idea how to implement it.