Symptoms
When the PreventPSTNTollBypass parameter in voice policy is set to true and the AllowNonEnterpriseVoiceUsersToDialOut parameter in conferencing policy is set to false in a Microsoft Skype For Business Server 2019 or Skype for Business Server 2015 environment, users who’re not enabled for Enterprise Voice unexpectedly can dial out from a conference.
Resolution
To fix this issue, install one of the following updates:
- For Skype for Business Server 2019, install the December 2019 cumulative update 7.0.2046.151 for Skype for Business Server 2019, Front End Server and Edge Server.
- For Skype for Business Server 2015, install the May 2020 cumulative update 6.0.9319.580 for Skype for Business Server 2015, Front End Server and Edge Server.