3-Way Calling and allows you to spontaneously add another caller during an ongoing phone conversation. With 3-Way Calling you effectively put your current caller on hold by hitting the "flash" hook button and dial out to make a new connection. Conference Calling, on the other hand, is a virtual meeting room where you can have up to 10 callers call in at a pre-specified time. You must be sure all your callers have the dial-in number and PIN for the call. 3-Way Calling is an included feature available to you at no extra charge. Conference Calling is an included feature available to you for an additional per-minute charge.