An item in today's newspaper (April 2017) reports that call blocking devices are to be installed on the landline phones of 1,500 people living at home with dementia to protect them from cold callers, scammers and "silent" phone calls (from call centres block-dialling thousands of people at a time).
The devices require all callers to the person's number to enter a PIN code, otherwise they won't be connected.
This particular news item refers to a UK government initiative linked to a brand called TrueCall (which I know nothing about so cannot comment one way or the other); but I thought I would share it in the hope that the same technology is becoming more widely available - it might be worth asking your telecoms provider if they offer it as a service, or are planning to, for example.
For elders living independently, or at least using their own phones independently, it could provide helpful protection from some of those lowlife swindlers preying on vulnerable people. And not before time.