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Teams audio/video (UDP)


Teams uses UDP packets to transmit audio and video in teams calls (if UDP is not blocked). The Teams audio/video (UDP) test therefore simulates a Teams audio call by sending UDP packets to the Teams TURN server. It checks if the latency and packetloss fulfill microsoft's recommondations and indicates that a user experiences call quality issues.


Parameter Value
Method MS-TURN
Number of measurements 60 or ~3.000
Warning threshold 100
Critical threshold 500
Status percentage 5%


Locate the issue

There are many possible root causes for Teams audio/video issues. Therefore, narrow down where and when issues occur. Use the general troubleshooting guide and try to answer these questions:

  • Is it a client-specific, local or global issue?
    • Are there other clients with similar issues?
  • Are there other related services with issues?
    • Are performance issue maybe caused by local connection issues or device performance issues?

If you find other services with issues also look at their test documentations.

Possible causes (status warning/critical)

DNS server misconfigured

A misconfigured DNS server might resolve hostnames to suboptimal addresses, meaning to server addresses that are not nearby.

  • Check the frontend server names of the Cloud connections on the system profile.


A page with further explanations for the DNS misconfigurations is currently under construction

UDP routing

If UDP packets are routed over many network hops (e.g. proxy server), the latency increases. Microsoft recommends to use a local breakout, a proxy bypass and no deep inspection for such packets.

  • Check if the packets are routed properly and adjust the settings on the firewall, proxy, etc.

Possible causes (status error)

Firewall blocks UDP

Some companies block UDP packets by default. Teams will use TCP packets if UDP is blocked, but this degrades the performance and might be the reason for Teams call quality issues.

  • Check if the firewall blocks UDP traffic on port 3478. If yes, consider opening that port.

Other network components block UDP

Not only the firewall is able to block UDP packets.

  • Use a program like WireShark to trace if the packets are blocked somewhere.