In all documentation seems bug:
^^^^^^^ not "start", but "stat"
Returns the RTP-Statistics from the RTP-Proxy. The RTP-Statistics from the RTP-Proxy are provided as a string and it does contain several packet-counters. The statistics must be retrieved before the session is deleted (before unforce_rtpproxy()).
Example 1.16. $rtpstat-Usage
I use FREE operation system: 3.8.2-calculate GNU/Linux