I talked to my therapist about how to deal with toxic or simply very difficult relatives (as I have that issue too in a way). She said that estrangement is perfectly fine way when communication is detrimental to you in many ways.

But then estrangement isn’t always possible and isn’t even always desirable

For those cases she advised to keep interactions and communication to a minimum.

You determine what that minimum is. For example come over for 30 minutes visits only. Keep phone conversations short, if conversation goes over what you determine sufficient then you excuse yourself. If phone conversations are upsetting use strictly texts or emails etc You choose what works. Even if you need to provide some care/assistance to such people, you can come over and help out, then leave.

Etc It’s been actually working better for me since.

In your situation you might not have to call back as he isn’t part of your life in a sense. But then again he is dying.

You could call and keep it short. Focus on talking about his health. If you want to tell him how you are doing tell him you have great new job that involves traveling. You can tell what you want to tell or you can tell nothing.

If he insists on asking you things tell him you got to go and you’ll call him later (if you think you might). Change topic or stop conversation immediately. Might not have to hang up per se but inform him that you have to go back to work.