As you can see, we developed a WebRTC application only for desktop browser and Android. Unfortunately, web technologies are better implemented in the browsers than in WebView. I hope at the nearest time the iOS WebView will support WebRTC, or we will be able to use Crosswalk on the iOS.
However, there are several solutions available. Let's look at a few of them.
OpenTok is complex paid solution that helps add video/audio calls to the mobile applications or to the website. You can see a detailed description, and the price on their website at https://tokbox.com/. In this case, you do not need to set up a server. It is just a service that provides the STUN and TURN functionality for you. Tariffs are based on call durations.
Tip
There is Cordova plugin for the service as well. You can find it at https://github.com/songz/cordova-plugin-opentok.
Android installation is pretty easy, but iOS configuration needs some effort.