Both three-way calls and conference calls let you talk to three or more people on the phone simultaneously. The difference is that a three-way call starts as a conversation between two callers before one of the callers adds a third person to the line.  Many conference calls operate using a conference bridge, which allows multiple people to join a meeting in different ways, including a web link, mobile app, web app, or dial-in number. Three-way calling does not require the use of a conference bridge.