This article is part of the Microsoft Lync Server 2010 Administration Guide: PowerShell Supplement.
Prevent New Connections to Lync Server
To prevent new connections to Lync Server, use the Set-Service cmdlet to pause the RTCSRV service (that is, the Front End service):
Set-Service –Name RTCSRV –Status Paused
For more information
It looks like the TRCSRV service can not be paused. When I use the cmdlet to pause the service, I get the failed message:
Set-Service:Service 'Lync Server Front-End(RTCSRV)' can not be suspended because the service does not support being suspended or resumed.