This Recommendation describes the frame relay network-to-network interface intended for the interconnection of public networks providing PVC and/or SVC frame relay data transmission service. The signalling at the NNI for frame relay SVC is applicable to Integrated Services Digital Networks (ISDN) supporting Recommendation Q.933 at the user-network interface and to public data networks supporting Recommendation X.36 at the DTE/DCE interface. Details of physical layer, data transfer and signalling procedures are provided. This revision replaces Recommendation X.76 (1995) and its Amendments 1 and 2.