Recommendation ITU-T G.8275/Y.1369 describes the architecture and requirements for packet based time and phase distribution in telecom networks. The architecture described is mainly applicable to the use of IEEE 1588. Details necessary to utilize IEEE 1588 in a manner consistent with the architecture are defined in other Recommendations. This revision of Recommendation ITU-T G.8275 (2017/08) provides the following updates: -Common Annex and Appendix material to G.8275.1 and G.8275.2 added as Annex C, Annex D, and Appendix VIII. Amendment 1 incorporates reference to IEEE1588-2019 and includes Appendix IX: Considerations on the use of IEEE1588-2019