A device installed at the customer premises that enables multiple services to share a single circuit. For example, an IAD might support simultaneous PSTN voice, packet voice or data, and video to share a single local loop.An IAD typically is installed by the telco or other service provider, and may run a combination of PSTN, Ethernet, IP, and frame relay or ATM protocols. See also ATM, Ethernet, frame relay, IP, local loop, protocol, and PSTN.