Lab Topology ------------ The lab used in this example is a hybrid environment: it includes both an on-premises deployment and an Office 365 tenant. The on-premises domain is the fictitious ``flexcorp.com``, and in addition to Active Directory this deployment includes Skype for Business Server and Exchange Server. When selecting a vanity domain name for our Office 365 tenant we had to use a domain that we actually owned. Thus, our end users' email addresses and SIP addresses use the domain ``vosslab.net``. It is not necessary to reveal the underlying topology - Exchange Server addresses, Skype for Business front end pools, and so on. As you will see, all that VOSS-4-UC requires is the addresses of the PowerShell proxies that it will use to communicate with the UC applications.