My mom is 89 and is about as technology challenged as they come. She has a landline and just lets all calls go to voicemail and if they identify themselves as someone she knows while leaving a message she will pick up. No need for caller ID. Even she knows not to rent a phone from the phone company anymore and most phones that you buy either have caller ID or are voicemail capable.
If my mom was able to figure this out I’m sure 99% of the people can do so as well. This is the woman who could not figure out how to work a new safety can opener.