Same issues with my wife's dad. Can't reliably dial or answer a phone anymore. 93yo
We used an amazon/alexa device for my him. Can talk to him through it, and listen in. Called "drop-in" He can call my wife through Alexa by saying "Alexa call (name)"
https://www.gearbrain.com/amazon-echo-alexa-drop-in-2528544583.html
Camera needs power. If you can run ethernet cable you can do POE.
We use reolink cameras (E1) for the same purpose, but they plug in.
I also set up an 'emergency button' for him with a wifi alarm system. It is set to call my wife if he presses the panic button. Used this one:
Amazon Alarm