You should get him a call blocker. If TrueCall exist in your part of the world I can highly recommend them. They have a few profiles available from mostly open to absolutely locked down with a whitelist.
Edit: https://www.truecall.co.uk/ Might be UK-only. Have a look anyway as it’ll give you some idea of what can be done.
I can believe it…whenever I visit my father in laws house, who is 82, he gets a phone call like every 10 minutes, and it’s almost always one of these.
You should get him a call blocker. If TrueCall exist in your part of the world I can highly recommend them. They have a few profiles available from mostly open to absolutely locked down with a whitelist.
Edit: https://www.truecall.co.uk/ Might be UK-only. Have a look anyway as it’ll give you some idea of what can be done.