Network Key Performance Indicators

When you make a Teams call your audio, video and screen sharing is sent over the network as streams of network "packets" - hundreds every minute. When networks are healthy, those packets should all arrive at their destination without getting lost or delayed during the journey. Teams calls are "real time" communication and can be affected by poor network performance.

The Teams software codecs are good at dealing with minor network quality issues by using techniques such as forward error correction (sending extra packets in case some get lost or delayed), and concealing lost or late packets by smoothing over any gaps.

We look at network quality for Teams calls using three Key Performance Indicators (KPIs); Microsoft has defined thresholds above which a stream or call is considered "poor". Teams software clients monitor these KPIs during the call, and record the average and maximum values at the end of the call.

Jitter

On a good network, our packets should arrive regularly and in order - if they don't (high jitter) it can cause audio to be "robotic" and hard to understand.

Jitter is expressed as a time (ms) value - the change in delay between successive packets.

Packet Loss

On a good network, packet loss is zero - everything sent makes it to the destination. When packets are being dropped, this can create the effect of missing parts of words, or cause choppy or frozen video.

Packet loss is expressed as the percentage (%) of packets lost compared to the total packets sent.

Round Trip Time (RTT)

Delays on the network cause packets to take a long time to reach their destination, so audio and video are also delayed. If round trip time is bad, normal conversational flow may be difficult and people talk over each other.

Round trip time is the time (in ms) it takes for a packet to travel to the destination and back.

Some delay is inevitable, particularly on long distance calls. For example, a good RTT between London and Paris is under 10ms, while between London and Sydney a good RTT is around 250ms.

Microsoft Thresholds

Microsoft publishes thresholds, above which a call is classified as poor.