OpManager primarily relies on Cisco's IP-SLA for monitoring the VoIP and the prerequisite therefore is, that the device should be a Cisco Router and must have IPSLA agent enabled on it. From IOS Version 12.3(14)T all Cisco routers support monitoring of VoIP QoS metrics. Cisco's IPSLA, an active monitoring feature of Cisco IOS software, facilitates simulating and measuring the above mentioned parameters to ensure that your SLAs are met. Cisco IP SLA provides a UDP jitter operation where UDP packets are sent from the source device to a destination device. This simulated traffic is used to determine the jitter, the round-trip-time, packet loss and latency. This data is gathered for multiple tests over a specified period to identify how the network performs at different times in a day or over a few days. The VoIP monitor gathers useful data that helps determine the performance of your VoIP network, equipping you with the required information to perform network performance assessment, troubleshooting, and continuous health monitoring.