This Recommendation 1 defines a single algorithm for assessing the speech quality of current and near future telephony systems that utilize a broad variety of coding, transport and speech enhancement technologies.Based on the benchmark results presented within the studies of ITU-T, an overview of the test factors, coding technologies and applications to which this Recommendation applies is given in Tables 1 to 4. Table 1 presents factors and applications included in the requirement specification and which were used in the selection phase of the ITU-T P.863 algorithm. It should be noted that the performance of the ITU-T P.863 algorithm under each individual condition in Table 1 is not reflected in this table. Additional and detailed analysis will be undertaken in the characterization phase of the ITU-T P.863 algorithm. Table 2 presents a list of conditions for which this Recommendation is not intended to be used. Table 3 presents test variables for which further investigation is needed, or for which ITU-T P.863 is subject to claims of providing inaccurate predictions when used in conjunction with these. Finally, Table 4 lists factors, technologies and applications for which the ITU-T P.863 algorithm has not currently been validated. Note that the ITU-T P.863 algorithm cannot be used to replace subjective testing.