- Panasonic 4 port digital extension card (DLC4) - Adds capacity for up to four KX-T7600, KX-T7400, KX-DT300 and KX-T7200 series phones, DSS, KX-T0151 and KX-T0155 cell station and voice mail- Maximum of one per system- To support Bluetooth with the KX-DT300 requires v.5 software versionKXTDA5171