Conference call

A call conference 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 .

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:
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.
In 2007, two companies began to offer users a way to initiate their own conference calls, with no conference bridge, PIN codes, or specialized equipment.