How DLCI work in WAN connection?

configuring a static Frame Relay map, is optional unless you are using subinterfaces. The Frame Relay map will map a Layer3 address to a local DLCI. This step is optional because inverse-arp will automatically perform this map for you. The syntax for a Frame Relay map is as follows:

Configure subinterfaces

If you are using a routing protocol in a hub-and-spoke topology, you will probably want to use subinterfaces to avoid the split-horizon problem. To configure a subinterface, remove the IP address off the main interface and put it under the subinterface. Configuring a subinterface involves assigning it a number and specifying the type. The following command creates point-to-point subinterface serial0/0.1

Terminal DTE ---> PAcket Switch DCE ----> Frame Relay WAN ---> Network DTE / Personcal Computer DTE