With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cvIfCountInRtp2Messages
Cisco Voice If Count In Rtp2 Messages
1.3.6.1.4.1.9.9.17.1.4.2.1.20
VINES protocol count of input RTP type 2 messages.
Back to CISCO-VINES-MIB MIB page.
IPHost Network monitor allows you to monitor cvIfCountInRtp2Messages on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco firewalls right now.