April 16, 2014

How to use Microsoft Lync 2013 Pre-Call Diagnostics (PCD) tool to test network connection

The Lync Pre Call Diagnostic Tool (PCD) is a client based application that allows Lync users to see how the current state of the network might impact the media quality of an upcoming call. PCD shows a graphical view of your network metrics including Network Mean Opinion Score (NMOS), packet loss and packet interarrival jitter. To use this app, you need to have a Lync account.


  • About to get on an important call? Run a quick test in On Demand mode to make sure it will go smoothly.
  • Run a test in on demand mode to look at your network’s performance over extended periods of time.
  • Diagnose trends with a view of historical test runs
  • Having trouble signing in to Lync? PCD’s Sign-in flyout can help you figure out where the issue is.

The app can be downloaded using Windows Store from here ->

Steps to use this Tool:

Click on Menu => options

On the PreCall Diagnostics Tool options Type your Lync ID (i.e. Sip Uri it would be in the format and select the below options and click ok.


Then click on Start Test, on the credential prompt type your credentials and the test will show the results as below.

  • Network Mean Opinion Score (MOS), which measures the network’s impact on the listening quality of the VoIP conversation. The network MOS rating ranges from 1 to 5, with 1 being the poorest quality and 5 being the highest quality.
  • Packet loss rate, which measures how many packets are lost during transmission. The packet loss rate is measured as a percent.
  • Interarrival jitter, which measures the variation in arrival times of packets being received. Interarrival jitter is measured in milliseconds (ms).
    Based on the above results you can conclude the call quality of your call from the unknown network.