Why skype? (Score 1)

Because ID10T's can install it. Its cross platform and easy to use. We use it to talk to my Cousin in Thailand or Korea. My Aunt and Uncle have it in Oregon. It is also able to punch through firewalls and NAT problems extremely well BECAUSE THEY USE SUPERNODES to connect the call.

Also here is a good "Whitepaper" on the skype protocall
http://arxiv.org/ftp/cs/papers/0412/0412017.pdf