Skype was "good" back then because it could pierce firewalls and nat setups with its p2p magic. See https://www.theregister.com/2003/10/08/how_does_skype_get_th

Skype was "good" back then because it could pierce firewalls and nat setups with its p2p magic. See https://www.theregister.com/2003/10/08/how_does_skype_get_through/ https://www.theregister.com/2003/10/08/how_does_skype_get_th... but if you look around you will find more info...