I found it's pretty easy to activate the Echo from a recording. Caused me all sorts of pain while editing my videos. :-) I had thought of a basic phone->Echo interface by getting the phone to actually activate it. Figured it might be a good way to demonstrate functionality of the product to someone. [I put in a feature request for the Echo to recognize dialing tones. So that it could communicate, QR-code style, with devices.] But right now, no, there is no way to do that.