scope:

This Standard defines the stage two of the Call Forwarding Unconditional (CFU) supplementary service for the pan-European Integrated Services Digital Network (ISDN) as provided by European public telecommunications operators. Stage two identifies the functional capabilities and the information flows needed to support the stage one service description. The stage two description also identifies user operations not directly associated with a call (see CCITT Recommendation I.130 [1]).

This standard specified according to the methodology defined in CCITT Recommendation Q.65 [2].

This standard does not formally describe the relationship between this supplementary service and the basic call, but where possible this information is included for guidance.

In addition this standard does not specify the requirements where the service is provided to the user via a private ISDN. This standard does not specify the requirements for the allocation of defined Functional Entities (FEs) within a private ISDN; it does, however, define which FEs may be allocated to a private ISDN.

This standard does not specify the additional requirements where the service is provided to the user via a telecommunications network that is not an ISDN.

This standard described one of the trhree versions of Call FOrwording supplementary service, when implemented usng the "forward switching" networ routing alogrithm and partial routing at the public/private network interface as contained in CCITT Recommendation Q.80 [3].

The description of full rerouting as described in CCITT Recommendation Q.80 [3] is outside the scope of this standard. 

The CFU supplementary service permits a served user to have the network send all incoming calls, or just those associated with a specified basic service, addressed to the served user's ISDN number to another number. The served user's originating service is unaffected. If this service is activated, calls are forwarded no matter wha5t is the condition of the termination.

This standard is applicable to the stage three standards for the ISDN CFU supplementary service. The term "stage three" is also defined in CCITT Recommendation I.130 [1]. Where the text indicates the status of a requirement, i.e. as strict command or prohibition, as authorisation leaving freedom, as a capacity or possibility, this shall be reflected in the text of the relevant stage three standards.

Furthermore, conformance to this standard is met by conforming to the stage three standars with the field of application appropriate to the equipment being implemented. Therefore, no method of testing is provided for this standard.