Sources tell TMZ Oksana used an app to capture Mel Gibson's rage ... though it's unclear which app she used.
The device itself will become relevant when the experts try and determine if the recordings were altered in any way.
For the record, there's also a sound editing app.
Oksana's spokesman, Steve Jaffe refused to comment.
Oh, one more thing. We're assuming she used a 3G model, because it didn't drop the call.