The present document defines the stage one of the Call Forwarding No Reply (CFNR) supplementary service for the
pan-European Integrated Services Digital Network (ISDN) as provided by European telecommunication operators.
Stage one is an overall service description from the users point of view (see ITU-T Recommendation I.130 [1]), but
does not deal with the details of the human interface itself.
The present document defines the interworking requirements of private ISDNs with the public ISDN.
In addition, the present document specifies the base functionality where the service is provided to the user via a private
ISDN.
The present document does not specify the additional requirements where the service is provided to the user via
telecommunications network that is not an ISDN but does include interworking requirements of other networks with the
public ISDN.
Interactions with supplementary services not listed in clause 7 are outside the scope of the present document.
Charging principles are outside the scope of the present document.
The CFNR supplementary service enables a served user to have the network redirect to another user calls which are
addressed to the served users ISDN number, and for which the connection is not established within a defined period of
time. The CFNR supplementary service may operate on all calls, or just those associated with specified basic services.
The served users ability to originate calls is unaffected by the CFNR supplementary service.
The CFNR supplementary service is applicable to all circuit-switched telecommunication services.
The present document is applicable to the stage two and stage three standards for the ISDN CFNR supplementary
service. The terms "stage two" and "stage three" are also defined in ITU-T Recommendation I.130 [1]. Where the text
indicates the status of a requirement (i.e. as strict command or prohibition, as authorization leaving freedom, or as a (...abbreviated)