# How does VoIP monitoring work in OpManager?

OpManager primarily relies on [Cisco's IP-SLA](https://www.cisco.com/c/en/us/products/ios-nx-os-software/index.html) for monitoring VoIP. The prerequisite is that the device should be a Cisco router with the IPSLA agent enabled. From IOS Version 12.3(14)T onwards, 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:

- Jitter  
- Round-trip time  
- Packet loss  
- 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.

Follow the below steps to add a VoIP monitor in OpManager:

- Go to **Network -> IPSLA**
- Click on the **Add VoIP monitor** button at the top right corner of the page, and enter the remaining details.

![Adding VoIP monitor in OpManager](https://www.manageengine.com/network-monitoring/faq/images/voip-mon-1.png)

Learn more about [adding VoIP monitor in OpManager](https://www.manageengine.com/network-monitoring/help/add-new-voip-monitor.html).