How to report Malicious Call using Skype for Business client?
You can do Malicious Call Tracing (MCT) using Skype for Business or Lync Server, which will be very useful because users can flag, marketing, harassing, threatening, or obscene phone calls. Immediately after hanging up, the users can select an option to report the call as malicious. When such a call is reported, a trace request is sent to mark the record of the call to monitoring database (LcsCDR), and an event is logged. Later Administrators can then identify or retrieve the calls, the calling number, and the gateway or SIP trunk over which the call was received using Skype for Business or Lync report.
But you must have Monitoring Server deployed for malicious call tracing to be used. Malicious Call Reporting is very easy using Skype for Business or Lync client:
Open Skype for Business client > Tools > Report a Call…
After Selecting "Report a Call..." option you will see below screen to allow report a call.
You can enable MCT using voice policy. Voice policy is a set of calling features that can be enabled or disabled to determine the Enterprise Voice functionality available to your users. Voice Policy has set of public switched telephone network (PSTN) usage records that define what types of calls are authorized to assigned user.
You can have User, Pool and site level voice policy. You can enable MCT using Skype for Business / Lync Control Panel or PowerShell cmdlet. Refer below PowerShell Command.
Use below PowerShell Command to grant PowerShell Voice Policy:
How to block Malicious Call?
You can find script written by fellow expert (Mark Vale) on Microsoft Gallery. Which will be very useful to block these calls.