You support a Microsoft Skype for Business Server 2015 on-premises environment that includes the
following:
an Enterprise Edition Front End Pool with three Front End Servers

a mirrored back-end SQL database

both the Front End Pool and Edge Pool use hardware load balancers (HLBs)

an Edge Server pool with two servers in perimeter network

The environment supports 10,000 users and runs in High Availability mode.
Some users report that they are unable to make outbound calls to specific public switched telephone
network (PSTN) numbers. When they attempt to do so, the call appears to be connected but then drops
with a fast busy tone, and then they receive the following error message: "Due to network error your call
cannot be completed at this time. Please try your call again."
You need to troubleshoot the issue.
Which centralized logging scenario should you use?