Phone calls with my oldest sister are almost always over 1 hour

She knows and I remind her I don't like to be on the phone that long. She is a pro at skirting around when I tell her I have to get off the phone. Yes, I'm a willing participant in that. Her manipulation gets under my skin! She's not mean, she's just lonely. Arrggh. I have to be firmer at setting boundaries. Double arrggh!