Welcome Riverratnita: I'm sorry about the situation with your sister. I have an sister with BPD traits and I've had the same experience with her hanging up the phone, because she gets angry over some silly thing. I've even had the experience of her starting an argument, when there wasn't one to be had (I agreed with her, but she started arguing and wouldn't let me get a word in)
Unfortunately, we can't change others, only the way we interact and react. Using validation can be very useful (or minimally, don't invalidate). Validation isn't about agreeing with someone, but acknowledging their feelings. Certain communication skills can be helpful as well. If you click on the links below, it will take you to tutorials/articles.
VALIDATIONCOMMUNICATIONS OVERIVEWSETTING BOUNDARIES The two threads below can be helpful for you to avoid arguments and drama. At the end of the article on the Karpman Drama Triangle, there is information about healthy communication triangles.
AVOIDING CIRCULAR ARGUMENTSbpdfamily.com/message_board/index.php?topic=118892.0;all
KARPMAN DRAMA TRIANGLEhttps://bpdfamily.com/content/karpman-drama-triangleHas your sister ever been treated for mental illness/disorder, with perhaps meds and/or therapy? Feel free to offer some examples of the boundary problems or communication problems and ask for input from others.