Yes. Maybe not at your full rate, any maybe implicitly as a part of your work contract (you are paid XX for YY hours and ZZ hours on call) but 100 times yes. A

Yes. Maybe not at your full rate, any maybe implicitly as a part of your work contract (you are paid XX for YY hours and ZZ hours on call) but 100 times yes. Anything which an employer asks you to do is work. All work should be compensated for. This include travel required for work, training courses, time spent waiting for work where you are not completely free to engage in what you'd prefer to do.