CONTENTS

 1     Introduction
        1.1     Purpose
        1.2     Scope
        1.3     Abbreviations
        1.4     Related Recommendations
        1.5     Methodology of availability specification
        1.6     Organization of this Recommendation
 2     ISDN 64 kbit/s packet-switched connection type (PSCT) availability performance
        2.1     PSCT availability function
        2.2     PSCT availability parameters
        2.3     PSCT availability objectives
 3     ISDN 64 kbit/s circuit-switched connection type (CSCT) availability performance
        3.1     CSCT availability function
        3.2     CSCT availability parameters
        3.3     CSCT availability objectives
 4     ISDN 64 kbit/s dedicated-circuit connection type (DCCT) availability performance
        4.1     DCCT availability function
        4.2     DCCT availability parameters
        4.3     DCCT availability objectives
Annex A - Sampling estimation of ISDN availability parameters
        A.1     Estimation of the availability state of switched ISDN 64 kbit/s connection type portions
                  A.1.1     Definition of the minimal test for PSCT availability state determination
                  A.1.2     Definition of the minimal test for CSCT availability state determination
        A.2     Procedure for estimating availability of switched ISDN 64 kbit/s connection type portions
        A.3     Procedure for estimating mean time between connection portion outages of switched ISDN 64 kbit/s connection types
        A.4     Statistical basis of Phase I minimal test with N = 4
        A.5     Application of the sequential probability ratio test (SPRT) to the Phase I minimal test for availability
                  A.5.1     SPRT test procedure
                  A.5.2    SPRT methodology
Annex B - Representative end-to-end availability performance of ISDN 64 kbit/s connection types
        B.1     Representative end-to-end design availability performance of ISDN 64 kbit/s packet‑switched connection type (PSCT)
                  B.1.1     Definition of the example end-to-end PSCT connections
                  B.1.2     End-to-end PSCT availability performance for the Case 1 and Case 2 configuration examples
                  B.1.3     Representative design availability performance of other ISDN 64 kbit/s connection types
        B.2     Derivation of the end-to-end "95th percentile" availability from "worst-case" availabilities of connection portions
Annex C - Related availability parameters
Annex D - Factors to be specified in reporting ISDN availability performance of 64 kbit/s connection types
        D.1     Planned hours of connection portion availability