Longman Dictionary of Contemporary English
Wiktionary
n. A call between more than two people; teleconference.
WordNet
n. a telephone call in which more than two people participate
Wikipedia
A conference call is a telephone call in which someone talks to several people at the same time. 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 sometimes called ATC (audio tele-conference).
Conference calls can be designed so that the calling party calls the other participants and adds them to the call; however, participants are usually able to call into the conference call themselves by dialing a telephone number that connects to a "conference bridge" (a specialized type of equipment that links telephone lines).
Companies commonly 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.
The more limited three-way calling is available (usually at an extra charge) on home or office phone lines. For a three-way call, the first called party is dialed. Then the hook flash button (or recall button) is pressed and the other called party's phone number is dialed. While it is ringing, flash/recall is pressed again to connect the three people together. This option allows callers to add a second outgoing call to an already connected call.
Usage examples of "conference call".
Those who knew Hiram Stonebraker were not surprised at the sudden conference call.
I should have moved off with the myth of the waiting conference call, and let Stan clean up the resulting mess.
We did the after-action nature take its course and listened to his shit for five more inquiry by secure conference call, but I recognize the name months, then let him die.
He'd just finished a conference call with his counterparts in Japan, Britain, Germany, Russia, and China.
Then you get a conference call set up immediately with the foreign ministers of the G-8.
Beverly Crusher chimed in from the other screen on a three-way conference call.
When all four were on line, they'd stage a conference call with the Vice President, who was still aboard Kneecap.