An informal human-to-human error correction protocol used in voice over frame relay (VoFR), voice over Internet Protocol (VoIP), and voice over Wi-Fi (VoWiFi). As packet networks are designed for data communications applications rather than isochronous traffic, levels of latency, loss, and error are variable and unpredictable in nature. Toll quality, real-time voice communications is highly intolerant of latency, jitter, loss, and error. So voice over packet networks is a challenge.When quality is less than acceptable and the meaning is lost, the Huh? protocol -- as in "Huh? What did you say?" -- must be invoked. If that fails, the next level is the hang up and call back protocol. Both protocols have been used extensively in cellular networks for many years. See also error control, isochronous, jitter, latency, protocol, real-time, toll quality, VoFR, VoIP, and VoWiFi.