VMware Smart Assurance VoIP Availability Manager is an VMware Smart Assurance Domain Manager, where a Domain Manager is a service-assurance application associated with a particular type of information-technology domain (networks, systems, applications, application services). For VoIP Availability Manager, the domains are unified messaging solutions. Each Domain Manager is autonomous in the sense that it maintains its own data models, repository, and problem signatures, and monitors and analyzes the discovered objects in its own domain.