Recommendation ITU-T P.805, Subjective evaluation of conversational quality, provides guidelines, methods, and procedures for designing, conducting and reporting the results of conversational tests. Conversational opinion tests allow the subjects involved to be in a more realistic situation that simulates the actual service conditions experienced by telephone customers. In addition, conversational opinion 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). They can be used to study overall system effects or specific degradations such as delay.