Which of the following is NOT considered a common source of voice latency?

• A. Propagation delay
• B. Queuing delay
• C. Processing delays
• D. Encryption overhead

Answer: (D)

Voice latency mainly comes from three kinds of delays: propagation, queuing, and processing. Propagation delay is the time it takes for the voice signal to traverse the physical path, increasing with distance. Queuing delay happens when packets wait in buffers at routers during congestion. Processing delays cover the time devices spend encoding, decoding, packetizing, and making forwarding decisions. Encryption overhead, while it can add some processing time, is not typically treated as a separate common latency source in standard voice-latency models; it’s absorbed into the overall processing delay. So encryption overhead isn’t considered a separate common source of voice latency.