The Mitel MH88524 (Dual 2-4 wire Circuit) provides two independent interfaces between4-Wire devices such as the MH88631 COIC (Central Office Interface CIrcuit) and a speech switch such as the MT8814 (Analog Switch Array), requiring only a single bidirectional switch per crosspoint. The MH88524 can accommodate two full duplex audio links. The device is fabricated as a thick film hybrid which incorporates various technologies for optimum circuit design and very high reliability.