[Freeswitch-users] is there a way to validate RTP is flowing after bridging two channels?

I have a need to bridge two channels together and then somehow verify that I am getting RTP packets from both directions. The need stems from a desire to detect a one-way audio situation in rare nat’ed scenarios where signaling gets established but one party may have restrictive firewall rules preventing his/her RTP stream from reaching the FS endpoint. Any ideas?