Call EventService.GetEventParticipantStatus
Get status for all participants of an event. Returns the EventId, EventName, RecipientId, EmailAddress, ExternalId, EventParticipantStatus (which can be Registered, WaitingList, CheckedIn, Decline, Cancel, NotRegistered), RgistrationDate, StatusUpdatedDate, EventSessionId, EventSessionName and Guests. Guests refer to the number of anonymous guests an event participant has added. Works only with Event 2.0 which is now DEPRECATED (Queued method)