Uniden DCX100 DECT 6.0 Cordless Telephone Accessory Handset with Caller ID DECT 6.0 Interference Free Cordless Frequency - (1.9 GHz Digital Enhanced Cordless Telecommunications) with extra handset V-Quad Technology (4 Way Voice Enhancer) and Conference Call - You can hold a 3-way conversation (conference call) between your handset, an external caller and another internal handset user. Handset Speakerphone - This feature gives you the freedom to use the handset as a speakerphone. Expandable - Register 6 Handsets to 1 Base Clearest voice reception and maximum security