With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cSipStatsTrafficInviteIns
Cisco Sip Stats Traffic Invite Ins
1.3.6.1.4.1.9.9.152.1.2.7.1
This object reflects the total number of INVITE requests received by the user agent since system startup.
Back to CISCO-SIP-UA-MIB MIB page.
IPHost Network monitor allows you to monitor cSipStatsTrafficInviteIns on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco mobile switches right now.