If none of the previous steps have solved the Frame Relay issue,
the problem may be related to Frame Relay encapsulation. Cisco routers default
to cisco Frame Relay encapsulation, which is valid only between other Cisco
routers that are using cisco Frame Relay encapsulation. If connecting to a
third-party router, the Frame Relay encapsulation must be changed from
cisco to ietf. To configure
ietf Frame Relay encapsulation, replace the
encapsulation frame-relay command with
encapsulation frame-relay ietf.