[Name] connectionid [Required] false [Attribute Constraints] Must not be used with conferenceid [Type] ECMAScript Expression [Default Value] none [Valid Values] Connection IDs [Description] 
An Optional ECMAScript expression which returns the identifier of a connection. If specified, the dialog being prepared MUST be joined to the referenced connection as specified by the mediadirection attribute. Note that if the referenced connection is already bridged to another media endpoint, those existing bridges may be affected according to the rules specified in section 10.4 even prior to being performed If the attribute value is invalid an error.semantic event must be thrown.