Shuffling releases more resources on the G4xx Media Gateway and Avaya Aura® Media Server than hairpinning does. Therefore, Communication Manager first checks both endpoints to determine whether Communication Manager meets the criteria for using a shuffled audio connection. If the shuffling criteria are not met, Communication Manager routes the call according to the criteria for hairpinning, if hairpinning is enabled. If hairpinning is not enabled, Communication Manager routes the call to the TDM bus. Both endpoints must connect through the same G4xx Media Gateway and Avaya Aura® Media Server for Communication Manager to shuffle or hairpin the audio connection.