KX-TDA600 Packages KX-TDA600 systems are best suited for large to extra large size business applications or large family estate or compound applications in the 12,000 square feet and above range with IP as something that one might want to work into but not employ today. Like the KX-TDA100 and KX-TDA200, the KX-TDA600 employs UCSD (Universal Card Slot Design). UCSD allows for any available card to be inserted into any available slot in any order. The KX-TDA600 Main Cabinet has a total of eleven (11) Universal Card Slots. Up to three (3) expansion cabinets may be added, each with a twelve (12) Universal card Slot capacity making the KX-TDA600 one of the largest Panasonic PBX systems available, second only to the KX-TDE600.