VTech DS6071 Accessory Cordless Handset, Silver/Black | Requires a VTech DS6671 Expandable Phone System to Operate DECT 6.0 Technology Accessory Handset Only - requires DS6671 Series to Operate Caller ID/Call Waiting*stores 50 calls HD Audio Full duplex handset speakerphone DSL Subscribers may need to us a DSL Filter For optimal performance batteries should be charged for 16 hours prior to use