I have bought everything I need to set up a VoIP landline, including a local phone number that can be used to call him from any regular phone.
The setup works on my Wi-Fi. But for some reason, it hasn’t worked very well on Regis’s Wi-Fi. Regis has been in the middle of upgrading their Wi-Fi. Given that it is not their top priority, it will probably take them a long time to complete their upgrades. But when they do, I will try again.
In any case, this solution will solve only SOME of the issues Dad currently has with his touchscreen phone.