What other options are out there that are (a) cross-platform and (b) can be set to auto-answer video calls? Skype has been in our plans for our poor man's Tele

What other options are out there that are (a) cross-platform and (b) can be set to auto-answer video calls? Skype has been in our plans for our poor man's Telepresence setup, but at the same time, I've never been super comfortable with relying on Skype, particularly with their bare-bones Linux support.