Tele-Path Instruments 650 Frame Relay Test Set is a compact, battery operated device used to conduct testing of Frame Relay circuits at the Customer Premise (CP) or User Network Interface (UNI). The TPI 650's operating modes allow it to function in a Terminating mode, acticng as the CSU/DSU and TE,DTE, or in Monitor mode allowing monitoring of an operational FRS circuit. With the optional FRS Stress Testing feature installed the unit can test a new network leg by generating various data rates and frame sizes in order to "stress" the network. The TPI 650 allows testing of a FRS circuit by emulating a CSU/DSU and TE and communicating toward the network at the UNI or emulating DTE and testing toward the CSU/DSU. Full T-1 or Franctional T-1 service is supported on the 4-wire Local Loop (DDS) Interface. The DTE interface supports all speeds up to 1.536 Kbps using TPI test cables. The TPI 650 allows the user to place a FRS data call, choose data call speed, cunduct PING testing, performing Bit Error Testing, and monitor DLCI's for troubleshooting testing.