Skype’s NAT Support Isn’t Special
Leave it to smart dudes like Aswath to dig in and discover, in Skype’s own documentation, that Skype’s NAT traversal system is none other than UDP hole punching, which is basically what every commercial VoIP provider does. Instead of deploying their own session border controllers, they essentially make the Skype users do the job. He also describes how to defeat it.
So at this point, the only things Skype has got going for it is that it’s got a softphone on a variety of platforms and uses wideband codecs for maximum audio quality. Yeah, the NAT traversal just works, but there’s no reason all that technology could not end up being depolyed over SIP.
Why is it the more I find out about Skype, the less impressed I am?