Rude conversation

Ok. It really bugs me when I’m having a conversation with someone (my mom in this situation) and they answer their phone and just walk away completely ignoring me and start having a full blown conversation with the person who called. Like I understand if it’s work or an emergency but seriously. If we are having a conversation and are literally in the middle of it and you with no warning just answer your phone and walk away like I don’t exist. I’m going to get pissed.