We've covered a lot in this article. I've shown you the fundamentals of RTTTL, provided you with an opportunity to do some musical thinking, and demonstrated how to use the RTTTL Player to listen to your creations.
In the next article in this series, I'll show you how I created the RTTTL Player using the Java Wireless Toolkit, and give you an introduction to programming your own wireless applications using the WTK.
I hope that you've found this article to be informative and thought-provoking. I also hope that you use what you've learned to create wonderful music. The world needs more wonderful music, not less.