In this chapter, we survey various ITU-T Recommendations to understand the methods developed for evaluating the perceptual quality of online real-time interactive multimedia applications (RIMAs). We summarize the documents most relevant to perceptual and objective multimedia quality, including Series E, G, H, J, and P of the ITU-T Recommendations. We classify the documents according to subjective assessment methods, objective perceptual quality models, quality-of-experience (QoE) schemes, and quality-of-service (QoS) models. For each category, we explain the key metrics and the applications most pertinent to perceptual quality. Our study reveals numerous subjective test methods, each focusing on specific aspects of a telecommunication system. There are no solutions that can fully address online RIMAs due to the multiple attributes related to one-way, two-way, or multi-way interactions. Our survey of objective perceptual quality models highlights their application-specific nature and limitations. In particular, models for online RIMAs must operate in no-reference mode without relying on the original multimedia data. However, the design of such models for one-way audiovisual streams remains an active area of research, with no viable models yet available for two- or multi-way communications. Our evaluation of QoE and QoS schemes also reveals similar limitations.