X.25 is often the only reliable WAN method, as many countries' phone systems are outdated and leased lines are not readily available. As a follow-on to X.25, frame relay will be popular in Europe, as well as for connecting U.S. sites to those abroad. Frame relay offers independent packet addressing, which also reduces overhead. Private virtual circuits may be set up between addresses. If you choose a public frame relay service, you'll need frame relay equipment on your premises, as well as a connection to the frame relay network via the local loop.
Most corporations use a router with a frame relay interface card.
You can also use a multiplexer, commonly referred to as a mux, that accepts data from the LAN and forwards it to the frame relay network.