Business class phone works with RCA® VoIP phone service (sold separately). Handles up to two calls per phone at the same time. Simply plug the base station into your existing Internet connection and it will wirelessly connect to the included deskphone. Mix and match up to six deskphones or cordless phones (both sold separately). Its Caller ID Memory can store up to 300 contacts. Full Duplex Speakerphone with HD voice. The Do Not Disturb feature allows you to mute while still maintaining all of the functions of the VoIP Phone. Digital Receptionist (auto attendant) is fully customizable and helps direct your callers quickly and easily to any extension. Three-Way Call Conferencing permits three separate phone callers to conference simultaneously.