It's been said that some Pirahã speakers can understand each other when they're are whistling or humming, because Pirahã is a tonal language. I take it this could be compared to speaking English without the consonants, so it would be quite ambiguous, but could work with set phrases - 27 words or so might coincidentally be just about as far as you'd get realistically. Solresol already has a dictionary, so you can use it, especially if your whistles are created by a device. But if you're going to whistle to the computer yourself you must have a perfect pitch, otherwise it won't understand you. Well, you could start the transmission by a triad (do-mi-sol) to let the computer tune into your pitch. That's a pretty cool idea, though. What kind of messages are you thinking of sending by whistling?