Contacts and Groups Management
A contact is a unified communication entity that is identified by a SIP URI. One or more contacts can be assembled into logical collections called groups. When a group is created, it is assigned a group ID, which is a server-assigned integer. The Contacts and Groups API in Microsoft Unified Communications Managed API (UCMA) 3.0 is available only for UserEndpoint objects.
For more information, see ContactGroupServices.