G4S Technology of Tewkesbury, Gloucestershire, United Kingdom, has expanded the integration of its Symmetry Security Management System with new intercom stations and IP loudspeakers from Zenitel Group of Brussels, Belgium. Triggers can be set within Symmetry to play prerecorded voice announcements and warnings. The system can address each speaker individually, enabling audio communication to be confined to relevant areas. Speakers are available in horn or ceiling models. Intercom stations are resistant to dirt, dust, water, and vandalism. An integrated acoustic echo canceller and an active noise cancelling function are configurable for different environments.