I've been spending some time looking at some of the significant changes Apple has made to Facetime in iOS 7. I'm far from an Apple fanboy but some of them are pretty interesting:
- multiplexing everything over a single UDP port - deflate compression with SIP - various /slight/ protocol violations ;)
More here:
http://blog.krisk.org/2013/09/apples-new-facetime-sip-perspective.html
As SDP bodies swell more and more can we hope to build significant support for multiplexing and deflate compression in the SIP-focused open source ecosystem?