Use webrtc or Peer to Peer for video calling IOS and android
I have been working in this space for the past few months now and webrtc on iOS is not easy. To help this problem I have added a github repo with a working example of and iOS app using webrtc.
https://github.com/gandg/webrtc-ios
The site references the google code site as well, so it should be a helpful starting point.
OpenTok has a native iOS SDK on WebRTC, which should be a good place for you to look into.
I've spend 2 days to research about WebRTC for mobile. I try to install webRTC for Android (follow webrtc.org) but it's too complicated. I just found 2 awesome project:
For server: https://github.com/pchab/ProjectRTC
For Android Client: https://github.com/pchab/AndroidRTC
Less than 15 minutes to install and it worked well.
About Client iOS, I think you should try gp-coder suggestion, use https://github.com/gandg/webrtc-ios.