What is Key Systems?

Key systems, also known as key telephone systems (KTS), are multi-line telephone systems typically used in small to medium-sized businesses. They allow multiple users to share a limited number of outside lines, providing features like intercom, call hold, and call transfer without the complexity and cost of a full PBX system. Key systems are characterized by having buttons on each phone corresponding to specific lines (outside lines or extensions), allowing users to directly select a line for outgoing calls or answer an incoming call on a specific line. While becoming less common with the rise of VoIP and hosted PBX solutions, key systems are still found in some environments due to their simplicity and reliability.