The Cisco IP/VC 3520 Videoconferencing Gateway -- also available as a desktop or rack-mountable unit -- is a device that translates between H.323 and H.320 protocols. This gateway lets users interconnect IP-based H.323 networks consisting of LAN-attached videoconference endpoints with legacy ISDN-based H.320 systems. The Cisco IP/VC 3520 Gateway offers two and four port configurations of Basic Rate Interface (BRI) or V.35 WAN interfaces. It supports up to four calls at speeds up to 384 kbps (BRI interfaces) or 768 kbps (V.35 interfaces).