If you're running Busylight for MS Teams 2.X or above, then more information is needed to determine where the issue lies, contact support here.

If you're running Busylight for MS Teams 1.5.7 or below, then it's because Microsoft hasn't updated their API for Teams Call Events, so we can't program a software integration for that feature. However, we do have a workaround for this for the people using Plantronics headsets. Click here for the guide.