Talking on the phone good for Mom but makes me crazy!!!!

When I can't visit my mom I try to call every couple of days.  This has become torture for me and those around me because Mom just can't hear.   She won't wear a hearing aid and the longer she talks the farther down her face - and away from her ear - slides the phone.   After 15 minutes I end up screaming the same things over and over, finally saying "never mind".    When i want to hang up it's a three stage process.  Stage 1, I tell her I need to get going for what ever reason then she asks what we'll be doing for the next few days.  Stage 2, I tell her I need to get off the phone for what ever reason, then she tells me what she's been doing - this is all after about 30 minutes of the very same conversation.  Stage 3, I tell her again that I'll have to hang up and she asks again where we'll be going next, her voice waivers and I can tell she's ready to cry.   By stage 3, she is asking, what? what? again and I'm yelling the same thing over and over...  I'm ticked off, my voice is louder and the tone lower.  Anyone around me is ready to grab the phone from my hand and slam it to the floor.

It's like having a little kid, I can't be mad at her because she just doesn't understand.  She NEEDS the calls and the company. She can't hear well, she's just happy to have a conversation with someone she loves and she knows loves her.  How can I rush that?  How can I hang up?  How can I NOT feel like crap for getting so frustrated.  I can't; it's just one of those things I have to live with .  I try to call her only from home where the only ones bothered are my husband and me.  I know it will take 3 tries to get her off the phone and I know she'll get weepy so I brace myself and get ready for the stages.  When she gets to the point that we DO NOT go through all 3, I'll know something is really wrong.