This Recommendation defines the access to Remote Frame Handlers from ISDN user-network interfaces. It specifies the signalling to establish, maintain and release circuit-switched bearers between ISDN users and Remote Frame Handlers mainly by referencing ITU-T Rec. Q.931. It specifies also the signalling to establish, maintain and release frame relay virtual circuits within an established circuit-switched bearer by referencing ITU-T Rec. X.36.

In addition, it includes the protocol for frame relay permanent virtual connection status monitoring, together with the corresponding Protocol Implementation Conformance Statements (PICS) proforma. This revision replaces ITU-T Rec. Q.933 (1995) and no longer supports case B of Q.933 (1995) whereby ISDN local exchanges provide frame relay services.

This revision of ITU-T Rec. Q.933 (2003) is in alignment with the latest release of ITU-T Recs X.76 (2003) and X.36 (2003).