Conflicted about contacting my sisters

I really need advice, I'm so conflicted. tl;Dr - My sisters called me and I really want to call them back, but I risk my parents answering who I've been no contact with. I moved out of my parents house about a year ago. I have two younger sisters who are both still living with my parents. My parents refuse to let me talk to them, because I'm not talking to my parents so why should I talk to my sisters? I have not talked to them since around Christmas when my grandmother called me so I could talk to them. My sisters supposedly called me today so that I could talk to them, but if I call back I risk my parents answering the phone. I miss them so much and I really want to call back so I can talk to them