Panasonic KX-TDA0177 16-Port Single Line Telephone Extension Card with Caller ID (CSLC16)16-Port SLT Card with Caller ID (CIDSLT16)Supports single line telephones (SLTs) with Caller ID (FSK)Includes 4 power failure circuitsRequires 1 free slotUseful in hotel applications where Caller ID-compatible s..