View source for Resource.subscribe

=== Parameters ===

;event : Keyword indicating the event: dialog (subscription to call state events), message-summary (message waiting subscription)
;operation : Keyword indicating the request: subscribe (request a subscription), unsubscribe (request to unsubscribe from event)
;expires : Integer indicating the subscription duration (if operation is subscribe). If 0, the subscription won't expire
;subscriber : The requestor
;notifier : The resource to subscribe to
;notifyto : The URI used as destination when notifying
;data : Data used by protocol