Skype for SIP lets peer-to-peer VoIP clients interact with existing IP PBXs. The company saw its user base grow to more than 500 million accounts in 2009 and is making a run at a new market this year. Most companies do not encrypt their VOIP traffic, a major flaw, says Michael Gough. Skype traffic is encrypted point A and point B, so it’s impossible to intercept a Skype call and encrypt it. Gough: A DDoS attack can happen at various layers with a VOIP system.”]