I'm with merlot here! (Alexa you can unplug a landline from the wall). But then, I'm inclined to ignore calls when my favourite TV programme is on, or if I'm immersed in something not easily left (like making a cake, e.g.), and call back later.
In the early days of telephones we had to answer every call as there were no means of tracking who the call was from after the event. I think this has given rise to a culture where people feel it's rude not to answer a call. Today we have the 1471 feature, or Caller Display, all calls listed on the phone etc. So we no longer need to be at the behest of anyone wanting to call and talk to us - at a time that is obviously convenient to them, but not necessarily to us.
And consider this: if someone interrupts a conversation without saying, 'excuse me', they are considered rude and ill mannered - indeed this is one of the very early things we instil in our children. Why then should we expect to have the right to interrupt someone by phoning them?