ITU-T Recommendations

This Recommendation provides specifications for transmission time, including delay due to equipment processing time as well as propagation delay, in connections with echo adequately controlled. Recognising that the delay became a limited resource in modern networks, the Recommendation is intended to assist network operators as well as equipment manufacturers in controlling the detrimental effects of delay (without echo) on service quality. All services with overall performance which depend on user or terminal interactivity are considered.This Recommendation is divided into three clauses. Clause 1 gives a general overview. Clause 2 provides recommendations for the end-to-end one-way transmission time limits. Clause 3 contains transmission time allocation guidelines for the national and international segments of the connection. Clause 3 guidelines apply only to the processing time portion of the delay. Additional information on how to estimate delay in international circuits and on the impact of long delays on the service quality is provided in the two annexes.