You don’t have to answer the phone. You can even turn off the ringer. No one is going to die because you didn’t answer their phone call.
For the few people in my life who are intrusive and manipulative, I *never* answer the phone when they call. This is effective for at least three reasons:
(1) It trains them to expect that they do not have instant guaranteed access to your attention, and after a while, they will demand it less and less.
(2) It preserves your attention for what you want to devote it to, and protects you from distraction.
(3) It allows you to pick times for communication that suit you, and to calmly prepare any scripts or other tools you may want to have ready before you initiate communication, rather than being taken by surprise and potentially being off balance and not ready to protect yourself as necessary from intrusion and manipulation.
There will definitely be pushback when you start doing this, as there is sort of a social expectation that when someone is home, they answer the phone. So you will have to go through some conversations like this, before callers adapt:
I called you this morning, but no one answered. Were you home?
Yes, I was home.
Really?? Then why didn’t you answer the phone??
I wasn’t able to come to the phone when you called.
I was doing something and I didn’t want to be interrupted.
What were you doing that was so important you couldn’t come to the phone??
What I was specifically doing isn’t important. I didn’t want to be interrupted.
What if it was an emergency???
If there is ever a health- or life-threatening emergency, you should definitely call 911 right away so that trained professionals can handle it.