Right now I'm paid for results. A little bit of availability. I have regular meetings that I have to attend, that involve meeting remotely with Asia. That requires me to be "on" when I'd rather be "off".
Prior to this, I had several years of working in, or managing, a 24/7 organization (manufacturing). Though I wasn't thrilled with the calls at night and on weekends, I much preferred the work.
And as I have children, I was out the door same time every day. In exchange, if something broke on the weekend, I usually fixed it. Many others would be conveniently "out of town" on weekends, or they didn't answer their phones. However, they were the ones to work late if shit broke at 5 pm.
If the amount of calls I got during "off" time wasn't regular, I wouldn't mind much. A few hours a month on the weekend - fine.