VTech LS6405 Accessory Cordless Handset, Silver | Requires a VTech LS6425, LS6475, LS6426, or LS6476 Series Expandable Phone System to Operate DECT 6.0 Digital technology Accessory handset onlyrequires a LS6425, LS6475, LS6426 or LS6476 series phone to operate Caller ID/Call Waiting*stores 50 calls Push-to-Talk HD Audio Handset speakerphone DSL Subscribers may need to us a DSL Filter For optimal performance batteries should be charged for 16 hours prior to use