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Teams audio/video (TCP)


The Teams audio/video (TCP) tests probes the connection to the Teams TURN server using the TCP protocol. Teams uses TCP connections for audio and video transmission if UDP is blocked. The Teams audio/video (TCP) test therefore replaces the Teams UDP test as an indicator for the audio and video quality in an environment where UDP is blocked.


Parameter Value
Method TCP
Number of measurements 58
Warning threshold 200
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 possibly 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.


If your clients use UDP for Teams then have a look at the Teams UDP test in case of Teams call quality issues.

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.

TCP routing

If packets are routed over many network hops (e.g. proxy server), this increases the latency. Microsoft recommends to use a local breakout, a proxy bypass and no deep inspection for such packets. Keep in mind that this test will bypass any configured HTTP-proxy server.

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

Possible causes (status error):

Firewall blocks TCP

The most likely reason for errors is that packets are blocked. However, this is unusual.

  • Check if the firewall blocks TCP traffic on port 443 going to If yes, consider to unblock this traffic.

Other network components block TCP

Not only the firewall is able to block TCP packets.

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