ContactGroupServices class contains services to add, delete, or update the contacts and groups of the session's owner.
Assembly: Microsoft.Rtc.Collaboration (in Microsoft.Rtc.Collaboration.dll)
Contacts are unified communication entities identifiable by SIP URIs that can be assembled into logical collections called groups. A Group is identified by a group ID which is a server-assigned integer. A Contact can belong to zero or more groups. Adding someone to the contact list does not automatically indicate that their presence information is subscribed to. The application must separately use the RemotePresence class to subscribe to these contacts. Groups do not hold references to their contained contacts.
These contacts and groups are cached locally when BeginSubscribe(AsyncCallback, Object) is invoked and are cleared if they have not been accessed for longer than five minutes. Subsequent usage of the APIs in this class causes the cache to be populated again.
The allowed operations are adding, deleting, and updating of contact and group properties. When a group is deleted, the group is automatically removed from all contacts belonging to that group.