Three-way calling enables three people to converse simultaneously. NTT's landline service (220 yen/month) lets users add a third party during a call. Mobile carriers offer it as "three-way" or "group calling."
Operation: during an A-B call, A presses the hook button to hold B, dials C. When C answers, pressing hook again establishes A-B-C three-way calling. Charges apply separately for A-to-B and A-to-C.
PBX conference call features enable multi-party calls beyond three. Cloud PBX and video call services (Zoom, Teams) have reduced traditional three-way calling usage.
Three-way calling is exploited in scams: criminal A calls the victim, says "I'll connect you to the bank," adds criminal B, making the victim believe they're speaking with a banker. Be wary when suddenly connected to third parties. See fraud prevention guide.