At our facility, we have on-call rotations for frozens, stats, emergency 
situations (processor alarms, etc.) Currently ours is a weekly rotation that 
pays $1.50 per hour (whoopee!), but the on-call time is Monday through Friday 
from 5 pm until the next morning at 5 am, weekends are 24 hours each for 
Saturday and Sunday. If we are called in, we are paid regular hourly wages 
for a minimum of two hours (even if we spend only 15 minutes doing a frozen 
section). 
  Hope this helps.