Panasonic Every digital telephone comes with a built-in "eXtra Device Port" (XDP) so you can instantly add a separate extension and use other communication devices simultaneously. Up to 192 CO lines Up to 448 Extensions Direct Dial In (DDI) Interface Attendant Console PABX System 2 to 16 Co Lines expanable 2 to 64 Extensions expanable Caller ID interface Direct Dial In (DDI) interface Business Centre service and more... Digital Super Hydrib System Take messages when you are on the phone or unavailable Be notified by extension message lamp of telephone Automate the handling of callers. (Interview and custom services) and more...