df570f0a_all_Control__CCXML_Version_1_0__Description
[Name] joinid [Required] false [Type] ECMAScript Expression [Default Value] none [Valid Values] (valid connection, conference, or dialog ID) [Description] 
An ECMAScript expression that identifies a connection, conference, or dialog ID that the new call must be joined to. This is equivalent, from the perspective of the CCXML application, to performing a immediately following the . However, platforms may use knowledge about the connection/conference/dialog to which the new call will be connected to optimize the call creation process. If the attribute value is invalid an error.semantic event must be thrown.
Voice Browser Call Control: CCXML Version 1.0