I am not sure if this answers the question, but I think it is somewhat related.
You can install the Ultimate Voice Recorder, which can record your conversations (very useful when calling customer service). Since he can record it, he must have some way of accessing the conversation.
In addition, the opportunities that you must provide to the application are quite scary (translated from Dutch: full Internet access, intercepting outgoing calls, changing preferences, direct calling of phone numbers, recording audio / recording, updating contacts, automatic launch). It seems to me that there must be something there that can help you?
However, I do not think that it can embed audio in a stream. The symbian version had the ability to embed audio signals into a conversation, but I don't think it has an Android version.
http://www.fingertip-access.com/
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