Residual Echo Return Loss measured at originating endpoint of this RTP session (i.e. the remote endpoint if this MIB is implemented in an endpoint). Note that this affects the conversational quality metrics reported by the terminating (this) endpoint, hence is useful in understanding what has affected the reported call quality mertrics A value of 127 indicates that this parameter is not available. In midpoint applications this parameter may not be available. If this is a midstream device and call quality metrics were calculated using the value of this parameter reported from the endpoint in an RTCP XR payload then the value used in this calculation MAY be reported.