This Recommendation provides guidance on the effect of end-to-end one-way delay (sometimes termed latency), and an upper bound one-way network delay.

While it is recommended that a one-way delay of 400 ms should not be exceeded for general network planning, it is important to appreciate that highly interactive tasks (e.g., many voice calls, interactive data applications, video conferencing) can be affected by much lower delays.

The effects of delays below 500 ms on conversational speech are estimated using a curve derived from the E‑model (ITU-T Rec. G.107).

This version constitutes a major revision of this Recommendation in order to align with other ITU-T Recommendations of the G.100 series.