Symptoms
A Survivable Branch Appliance (SBA) user can't escalate a PSTN call to a conference call if the SBA user is trying to add another PSTN user to the call and if Location-Based Routing (LBR) restrictions are enforced in Microsoft Skype for Business Server 2019.
Resolution
To fix this issue, install the December 2021Â cumulative update 6Â for Skype for Business Server 2019, Core Components.
