Recommendation ITU-T P.863.1 provides some important remarks that should be taken into account in the objective quality evaluation of speech conforming to [ITU-T P.863]. Users of [ITU-T P.863] should understand and follow the guidance given in this Recommendation. This Recommendation forms a supplementary guide for users of [ITU-T P.863], which recommends a means of estimating listening speech quality by using reference and degraded speech samples. The scope of [ITU-T P.863] is clearly defined in itself. This Recommendation does not extend or narrow the scope, but provides necessary and important information for obtaining stable, reliable and meaningful objective measurement results in practice.