Vorlage 3b

Table 2: Cause values and location in case of release of set-up of a CC link by the ISDN delivery network ITU-T Q.850 (05/98) Cause Definition Location Failure caused by Responsibility value

27 Destination Out of Order Other than user ISDN-DN or LEMF PTSS (0000)

31 Normal, Unspecified Other than user MD or ISDN-DN or PTSS (0000) LEMF

38 Network Out of Order Other than user ISDN-DN or LEMF PTSS (0000)

41 Temporary Failure Other than user ISDN-DN ISDN-DN (0000) Provider

102 Recovery on Timer Expiry Other than user MD or ISDN-DN or PTSS (0000) LEMF

111 Protocol Error, Unspecified Other than user MD or ISDN-DN or PTSS (0000) LEMF

Area of responsibility of CSP LEMF site nonnon --coincidentcoincident LEMF MDMDMD LILI--HPHP

Access LineAccess LineAccess Line NTNTNT GWGWGW LELE DNDN--HPHP MD Hosting Facility DN ProviderDN ProviderDN Provider DN ProviderDN ProviderDN Provider Area of responsibility FacilityFacilityFacility FacilityFacilityFacility of PTSS Area of responsibility of ISDN--DN ProviderDN Provider

InitialInitialInitial AddressAddressAddress MessageMessageMessage (IAM)(IAM)(IAM) SETUPSETUPSETUP MessageMessageMessage ReleaseReleaseRelease MessageMessageMessage (REL)(REL)(REL) DISC/REL/REL COMDISC/REL/REL COMDISC/REL/REL COM MessageMessageMessage TargetTargetTarget ‘‘‘sss subsequentsubsequentsubsequent MessagesMessagesMessages accordingaccordingaccording to ITUto ITUto ITU ---T Rec. Q.931T Rec. Q.931T Rec. Q.931 CommuniCommuniCommuni --- ReleaseReleaseRelease CompleteCompleteComplete MessageMessageMessage (RLC)(RLC)(RLC) cationcationcation

ttt

LostLostLost contentcontentcontent

Figure 25: Signalling sequences in case of rejection of set-up of a CC link by the LEMF

Unless otherwise stated in Table 3, the REL messages at the handover point between the CSP and the ISDN-DN provider and at the handover point between the PTSS and the ISDN-DN provider contain the same cause value indicating the location of the error.

The LEMF is not required to support all the cause values of Table 3. Table 3 merely indicates how the cause values shall be interpreted by the receiving entity. In principle, all the CSP needs to know is whether the error lies in the LEMF. The detailed determination of the reason falls under the responsibility of the PTSS. As the PTSS itself knows the status (all cause values are given by the LEMF), it does not need a separate message from the CSP or the ISDN-DN provider.