Im trying to find out if a company can legally scheadule a person for 6 days a week of work then call that person off work on a day by day basis

i work for a hotel in las vegas my position is On call however instead of calling when they need me, they post a scheadule of up to 6 days of work (8 hours a day) then they will call on the days they dont want me to work on the day im scheaduled for. this is making ti impossible for me to find a second job or for my husband to find a job because we never know what days i will actually have off. and with three kids at home someone has to be there to watch them. the people that do the scheaduling tell us worked that noone is to get more than 28hours a week of work so we cant get unemployment benefits or health care benefits. and im trying to find out if it is illegal for this company to do it.