A packet interface protocol that adheres to the ANSI/ITU-T standard. Frame relay has a few advantages over ISDN. For one thing, you can purchase frame relay lines in increments between 56K and 1.5 Mbps (equivalent to a T1 connection). Also, the protocol has a flat-rate billing structure instead of a per-hour usage charge. However, since frame relay is designed for data transfer only, it's not well suited for video conferencing or any other voice application.
Frame relay is sometimes confused with a leased line. Both are primarily used to extend a local area network (LAN) between business branches, but a leased line is a dedicated line (permanently connected between sites), whereas frame relay uses the telephone company's shared network on an as-needed basis.