Panasonic KX-TDA5171 4-Port Digital Extension Card DLC44-Port Digital Line 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 mailCapacity: 1 per systemTo support Bluetooth with the KX-DT300 requires v.5 ..