Unfortunately equating synchronous (i.e. realtime apps. such as VoIP/video) with asynchronous communications (i.e. email/IM/web application) creates a false perception of what security objectives are required in order to protect VoIP or any other real-time multimedia application. Indeed several existing security concepts can be used to provide protection. Some of the questions that typically need to be addressed are: (a)are these security concepts currently being implemented by products, (b) what are the requirements for real-time applications, (c) how effective are the current solutions?

Approach it as you were to build a car for the right purpose. Traveling across the Antarctic versus wining Formula-1 requires that the vehicles maintain different properties specific to the objectives of the mission (i.e. durability versus speed). Although in both cases the vehicles will have wheels, an engine (with different horse power), seats and a chasi they will differ greatly according to the objectives of the mission/purpose.

So, indeed conceptually we can use current methods to protect VoIP. But how we do that properly is a question that several people in the industry are working on.

Peter