"A conference call is a telephone call in which the calling party wishes to have more than one called party listen in to the audio portion of the call. The conference calls may be designed to allow the called party to participate during the call, or the call may be set up so that the called party merely listens into the call and cannot speak. It is often referred to as an ATC (Audio Tele-Conference).

Conference calls can be designed so that the calling party calls the other participants and adds them to the call. In most cases, the participants are able call into the conference call themselves. They do so either:

by dialing into a "conference bridge" (a specialized type of equipment that links telephone lines), or
by using a special telephone number set up for that purpose.
Usually, most companies use a specialized service provider who maintains the conference bridge, or who provides the phone numbers and PIN codes that participants dial to access the meeting or conference call.

Three-way calling is available (usually at an extra charge) for most customers on their home or office phone line. To three way call you call the first person you wish to talk to. Then you must press the Hook Flash button and dial the other person's phone number. While it is ringing press flash again. This will put your three people together. This option allows callers to add a second outgoing call to an already connected call.