How to get a PhoneCallId

SELECT
  ActivityPartyBase.PartyId AS ContactId,
  ActivityPartyBase.ActivityId AS PhoneCallId
FROM

CampaignActivityBase
INNER JOIN ActivityPointerBase

ON (ActivityPointerBase.RegardingObjectId = CampaignActivityBase.ActivityId)AND (ActivityPointerBase.DeletionStateCode = 0) 

INNER JOIN PhoneCall 

ON ((PhoneCall.ActivityId = ActivityPointerBase.ActivityId) AND (ActivityPointerBase.StateCode = 0) AND (PhoneCall.DeletionStateCode = 0))

INNER JOIN ActivityPartyBase

ON ((PhoneCall.ActivityId = ActivityPartyBase.ActivityId) AND (PartyObjectTypeCode = 2))

INNER JOIN ContactBase

ON (ContactBase.ContactId = ActivityPartyBase.PartyId) AND (ContactBase.DeletionStateCode = 0)


WHERE 
  (CampaignActivityBase.ActivityId = @CampaignActivityId)