I'm glad you were firm. It's a really hard thing to do.

Is there any way you can ask one of your siblings to be the primary contact? Perhaps ask him or her to call her and check on her a couple of times a day (or stop by like you do if they live in the area)? That would serve a couple of purposes - it might help your mother realize that she doesn't specifically have to have you do everything for her (others can do it, too) and it'll help your siblings understand what you go through on a daily basis.

Caregiving is a really tough job. Everyone who does it deserves a break now and then and this program is important for you. It's also important that you not get dragged into her drama 5 times a day while you're there. That'll distract you so much from the purpose of the program.

I think what I would do is leave mom with a list of numbers she can call and tell her that I will answer voicemails twice a day, but will not pick up the phone any other time. Boundaries.