The number of RTP packets received by the remote end point from
this MG on this flow. Comparing this with the local number of
RTP packets sent from this MG to the remote endpoint gives an
indication of how many outgoing packets were dropped on this
leg of the call. This information is from RTCP packet. Not all
endpoints report this statistic, if it is not available it will
be set to zero. This statistic will not be available for
signaling flows.