1, I used to work for this company when I was young and had no idea what my rights were. They very much took advantage of this, such as calling me in on an hour's notice on my days off.
I had a strict I don't answer the phone when not working policy. They could attempt to call me in but it wouldn't be recieved. If they asked me while I was at work I usually said yes, but I'm not about to come in on an hours notice for the same rate of pay, if you want on call, pay for on call.