There are two types of trusted applications. The two types differ by the type of endpoint used:

• Communication- and collaboration-enabled applications use ApplicationEndpoint.
  
  
• Middle-tier client applications that emulate Microsoft Office Communicator use UserEndpoint.
  
  

Examples include Automated Call Distributor, Instant Message (IM) Bot, Interactive Voice Response, Conference Bridge, and Personal Virtual Assistant.

An ApplicationEndpointendpoint designates a service involving communications, possible user interactions, and collaborations. It is represented by a Contactobject in Active Directory. It can communicate, using IM or audio, with one or more remote parties, and can collaborate using presence (through Enhanced Presence subscription and publication). ApplicationEndpointcan be assigned a SIP URI and a Dialed Number Identification Service (DNIS) telephone number.

Applications that require multimodal communications or presence must register against Office Communications Server.

ApplicationEndpointis globally trusted and uses server permissions. It is highly available.

ApplicationEndpointload balances communications across multiple Front End Servers.

Examples include Web clients.

A UserEndpointdesignates an Information Worker endpoint. An Information Worker is represented by a Userobject in Active Directory. A UserEndpointendpoint is assigned an Address of Record (AOR) and registers against Office Communications Server.

UserEndpointis not globally trusted and cannot impersonate another user or join a conference as a trusted user.

UserEndpointcaches one connection that is used for all its communications and collaborations.