The tone generation module provides for the generation of cadenced tones, suitable for a wide range of telephony applications.
Oscillators are a problem. They oscillate due to instability, and yet we need them to behave in a stable manner. A look around the web will reveal many papers on this subject. Many describe rather complex solutions to the problem. However, we are only concerned with telephony applications. It is possible to generate the tones we need with a very simple efficient scheme. It is also practical to use an exhaustive test to prove the oscillator is stable under all the conditions in which we will use it.