Jitter

Jitter refers to the variation in time between the arrival of voice data packets. In an ideal network, packets arrive at perfectly regular intervals. When they arrive unevenly — some early, some late — the result is jitter, which can cause choppy, garbled, or robotic-sounding audio.

Jitter is measured in milliseconds. For VoIP, jitter below 30 ms is generally acceptable. Jitter buffers in softphone clients temporarily store arriving packets and play them out at a steady rate, smoothing out variations.

While latency is the overall delay, jitter is the inconsistency of that delay. Both affect MOS scores and overall call quality. Proper QoS configuration helps minimize both.