>The approach we take (and others like Oracle, JBoss, Avaya, etc) is to deploy apps in SIP Servlet containers (Java) and your media in dedicated media servers (C/C++ for example).

Which makes sense for IVR or other media heavy applications. However, Twilio seems to get a lot of people using it for call tracking and click to call...shouldn't touch a media server unless (and I have heard of people doing this) they use media to conference two people....

But, perhaps those aren't the kinds of applications leading to scaling problems...