Uniden DCX770 Accessory Handset and Charger for DMX700/DCT600 Series Expandable Phones (Silver/Black) 2.4 GHz frequency-hopping digital spread spectrum signal For use with Uniden DMX7 (DMX776, DMX778, and others) systems Also works with DCT6/DCT7 systems Supports caller ID/call waiting, 100-number caller ID memory Recordable ringer tones, handset speakerphone, 10-number speed dial