Three-way calling lets three people talk at the same time. NTT East and West offered it on landlines under the name "Triophone," but that service ended in January 2024 as the landline network moved to IP. As of 2026, holding a three-person call from a landline means using a conference call service instead. Mobile carriers still offer the feature under names such as "three-way calling" or "group calling," but the name and whether an application is required differ from carrier to carrier. Office business phone systems and PBXs provide the same thing as a conference call feature.
The basic flow is that while A and B are talking, A puts B on hold, dials C, and once C answers all three are connected. On a landline this uses the hook button; on a mobile it uses the hold and dial controls on the call screen. Unlike call waiting, which switches between calls, three-way calling keeps all three voices connected - that is its defining feature. Each leg is billed to whoever placed it: A pays for the call to C, while the charge for the A-B call falls on B if B was the one who called A. Because everyone hears everything once the third party joins, it is good manners to tell both sides before connecting them.
In business, the conference call feature of a PBX allows calls with more than three participants. Cloud PBX and video call services (Zoom, Teams and the like) are also used at work, so as of 2026 there are more ways to hold a multi-party discussion without a phone line. Even so, when the other person only has a landline, or when you need a third party to confirm something on the spot, a three-way call over the phone is quicker.
Three-way calling is also abused in scams. Criminal A calls the victim, says "I will connect you to someone from the bank," and adds criminal B to the call so that the victim believes they are speaking with a bank employee - a "staged" scam. Be careful whenever a call is suddenly handed over to a third party. See the guide to preventing bank transfer fraud as well.