Recommendation ITU-T G.8272.1/Y.1367.1 specifies the requirements for enhanced primary reference time clocks (ePRTCs) suitable for time and phase synchronization in packet networks. It defines the error allowed at the time output of the ePRTC. These requirements apply under the normal environmental conditions specified for the equipment. Amendment 2 to Recommendation ITU-T G.8272.1 (2016/11) provides the following updates: -Added case where ePRTC includes an integrated T-GM clock