I'm disappointed to discover that only the desktop version (Windows/MacOS) of AIR 2.7 has echo cancellation support. AIR 2.7 for all mobile platforms do not have it! They should have used a different version number for them, since obviously, the features are different.
I was hoping 2.7 would solve all the audio problems folks had been complaining about. There's no word of when Adobe will put this echo cancellation feature into the mobile versions.
Anyhow, the latest release of ReelPortal app (v1.0.5) has code to use it, just like the desktop version. So it should automatically be enabled in whichever AIR version Adobe chooses to provide the feature.