frame relay 
This is a packet interface protocol for transmitting data at high speeds inexpensively. Data is packaged into small chunks called frames and sent without error correction (the latter is handled at the end point of the transmission, which speeds up the transmission rate). Frame relay is best suited for data transfer; videoconferencing or any other voice application requires continuous transmission, which frame relay's structure cannot provide. Frame relay is sometimes confused with a leased line. But while both are used primarily to extend a local-area network (LAN) between business branches and to connect wide-area networks (WANs) to larger backbones, a leased line is a dedicated line permanently connected between sites. When you sign up for frame-relay service, you purchase incremental bandwidth (56Kbps and up) on a provider's T1 line, and you use the service on an as-needed basis.