Gegensprechanlage

Gegensprechanlage, literally “two-way intercom” in German, refers to an electrical or electronic system that enables two-way audio communication between a person at an entry point and someone inside a building. It is typically used to verify identity and to authorize access, for example at a front door, gate, or lobby desk. Modern variants may include video, but the core function remains communication and door release control.

Key types include audio-only intercoms and video intercoms that add a monitor or camera at the indoor unit. Systems can be analog or digital; newer installations commonly use IP-based networks, enabling remote access, mobile apps, and integration with building-management systems.

Common components are the outdoor or entry station (door station) with a microphone, speaker, and call button; one or more indoor stations or monitors; a power supply; cabling; and a door-release mechanism such as a strike relay or electric lock. IP systems may use Ethernet and Power over Ethernet (PoE) and may support SIP or other protocols.

Operation typically involves a visitor pressing the call button; the indoor unit rings or alerts the resident; the resident talks and grants access by activating the door release. Some systems require authentication, such as an access code or a remote confirmation via an app.

Applications and security: Gegensprechanlagen are common in apartments, office buildings, and gated properties. Security considerations include eavesdropping, tampering, and unauthorized access. Digital and IP-based models can provide encryption, access logs, and integration with access-control systems, but they require proper network security measures.

History and evolution: Basic audio intercoms appeared in the mid-20th century and evolved to include video and digital networking. Today, many systems use IP technology and standard protocols, allowing cloud-based management and smartphone access.