On call on days off

What are the rules about being on call over days off? I work in a public hospital.

Under sub clause 4(xvii) (Hours of Work) of the Public Health System Nurses’ and Midwives’ (State) Award, no employee will be required to remain on call on a rostered day off or on the completion of a shift prior to a rostered day off. The only exception is in “extreme circumstances” (as agreed to by the employer and the Association) to enable the provision of services by a public hospital, A higher allowance is payable as set out in sub clause 12(ii) and Table 2 of the Award if on call does occur on your days off.