Codec Loss

The percentage of time the codec plays fill frames due to lack of valid RTP frames. Possible causes include jitter and packet loss.

Every RTCP interval

Average Codec Loss

The average codec loss measurement since the beginning of the RTP stream

At the end of the session

Codec RTT

An estimation of the overall Round Trip Time (RTT) on the voice-channel, including the network delay and internal delays.

RTT is the time taken for a message to get to the remote peer and back to the local receiver.

Each time an RTCP packet is received

Echo Return Loss

The echo cancellation loss on the TDM bus

Every RTCP interval

Loss

The estimated network RTP packet loss.

The VoIP engine evaluates the current received packet loss every RTCP interval – usually 5 to 8 seconds. The VoIP engine postpones loss estimation until the next interval if the number of packets received is less than the minimum statistic window. The minimum statistic window is configured with the CLI command rtp-stat min-stat-win.

Every RTCP interval

Average Loss

The average packet loss evaluation since the beginning of the RTP stream

At the end of the session

Remote Loss

The network loss according to the remote RTP receiver. The device learns of the remote packet loss from received RTCP messages.

Each time an RTCP packet is received

Average Remote Loss

The average remote network loss measurement since the beginning of the RTP stream

At the end of the session

RTT

The network RTT. This metric does not include internal delay. The device learns of the RTT from RTCP messages.

Each time an RTCP packet is received

Local Jitter

Variation in delay of packet delivery to the local peer

Every RTCP interval

Remote Jitter

Variation in delay of packet delivery to the remote peer. The device learns of the remote jitter from RTCP messages.

Each time an RTCP packet is received

SSRC Changes

The number of times the RTP SSRC field in received RTP packets has changed

Every RTCP interval