AT&T E598-1 Accessory Cordless Handset, Silver/Black | Requires an AT&T E5901, E5902B, E5903B, E5911, E5912B, E5913B, E5914B, E5921, E5922B, E5923B, E5924B, E6001, E6002B, E6012B, E6013B, E6014B, or E3813B Expandable Phone System to Operate 5.8 GHz Digital Spread Spectrum Handset Speakerphone Lighted Keypad & Large Display Caller Id & Call Waiting 50 Name / Number Caller ID Log