ITU-T Recommendation P.805 describes methods and procedures for conducting conversation tests to evaluate communication quality. The methodology uses examples of scenarios, rating scales and analysis procedures to estimate the subjective quality of telecommunication services. Conversation tests allow the simulation of more realistic situations close to the actual service conditions experienced by telephone customers. In addition, conversation tests are designed to assess the effects of impairments that can cause difficulty while conversing (such as delay, packet loss, echo, interruptions, noise, clipping, etc.), and may be used to study overall system effects or specific degradations as well.