Panasonic KX-TDA0168 8-SLT Extension Caller IDSingle Line Extension Caller ID Card (SLT CID)Mounts on the KX-TDA0173 8 port single line extension card (SLC8) onlyAllows the system to pass caller ID information to single line devicesRequires TDA version 2 software or higherSupports Bell/ETSI FSK only..