Since there are few hardware standards for Android devices, some may include hardware audio pre-processors and some won’t. Some Android devices don’t even have echo cancellation support for native phone calls. Red5 Pro mobile SDK uses AEC to control echo and feedback, but that is not supported by all Android devices. As a workaround, we suggest that you require headphones for two-way communication in Android.
iOS devices have hardware audio pre-processors, so that makes echo cancellation easy on that platform.