Thats comparing two vastly different parts of their respective networks though - its a bit like comparing Apples and Volkswagens. No ONE DNS server is as reliab

Thats comparing two vastly different parts of their respective networks though - its a bit like comparing Apples and Volkswagens. No ONE DNS server is as reliable as a Class 5 Telephone Switch. The telephone network is on whole more reliable than any single component of the internet - and its certainly more reliable that the internet on whole. The internet however is more survivable - much more, because there are less common choke points to fail. In a way you are correct though - nearly every component required for internet access is unreliable (because you can substitute another one with ease) whereas every network element in a phone call is much more reliable (because beyond a certain point, you cannot).