Ironically, one of the few exceptions to this is in transmitting the human voice. Real-time voice communications, such as Skype, typically do not use TCP, which underlies most of the rest of the Internet. As researchers discovered in the early days of networking, using reliable, robust protocols—with all their ACKs and retransmission of lost packets—to transmit the human voice is overkill. The humans provide the robustness themselves. As Cerf explains, “In the case of voice, if you lose a packet, you just say, ‘Say that again, I missed something.’”
