VTech 20-2420 Accessory Handset, Gray/Black | Requires a VT20-2400 Series Expandable Phone System to Operate Accessory handset for VTech models VT20-2431, VT20-2481, and VT20-2489 2.4 GHz digital spread spectrum signal Supports 2 lines, intercom, conference calling Built-in speakerphone Caller ID compatible