There is a maxim in the technology industry that states, “As soon as something is made idiot-proof, nature will invent a better idiot.” The point of this statement is that there is no development effort that can be considered complete. There is always room for improvement.

When it comes to security, you must always bear in mind that the people who are looking to take advantage of your system are highly motivated. No matter how secure your system is, somebody will always be looking to crack it.

We’re not advocating paranoia, but we are suggesting that what we have written here is by no means the final word on VoIP security. While we have tried to be as comprehensive as we can be in this book, you must accept responsibility for the security of your system.

As free Internet calling becomes more common, the criminals will be working hard to find weaknesses, and exploit them.