Voice and video services (circuit emulation) allow you to interconnect existing T1/E1 interfaces and other kinds of constant bit rate (CBR) equipment. CBR services include such features as PBX interconnect, consolidated voice and data traffic, and video conferencing.With circuit emulation, data received from an external device at the edge of an ATM network is converted to ATM cells, sent through the network, reassembled into a bit stream, and passed out of the ATM network to its destination. T1/E1 circuit emulation does not interpret the contents of the data stream. All the bits flowing into the input edge port of the ATM network are reproduced at one corresponding output edge port. An emulated circuit is carried across the ATM network on a PVC, which is configured through the network management system.The ATM-CES port adapter offers two types of services: circuit emulation service internetworking function (CES-IWF) and network timing.