The iPhone 4S really sends raw audio data. It’s compressed using the Speex audio codec, which makes sense as it’s a codec specifically tailored for VoIP.

The iPhone 4S sends identifiers everywhere. So if you want to use Siri on another device, you still need the identfier of at least one iPhone 4S. Of course we’re not publishing ours, but it’s very easy to retrieve one using the tools we’ve written. Of course Apple could blacklist an identifier, but as long as you’re keeping it for personal use, that should be allright!