Thank you for asking this question in the support community forum. The NV3430 does not support analog voice, which is typically the cause of echo on a network. All the voice traffic will just be "data" to the NV3430 (unless it is a SBC unit, or acting as a SIP proxy). With that said, there are multiple reasons echo could be present on a VoIP network, as well as many ways to treat the symptoms, but it depends on the network design and application. Often, echo is caused by delay and latency in a VoIP network. The typical solutions to echo are elimination at the source (two-wire interfaces in the network), echo suppression, and echo cancellation. For this application, there is little that could be done on the NV3430 to reduce the echo in the voice network.
I hope this makes sense, but please, do not hesitate to reply to this post with any additional questions or information. I will be happy to help in any way I can.