Scope:

This International Standard specifies the Transit Counter additional network feature (ANF-TC), which is applicable to various basic services supported by Private Integrated Services Networks (PISN). Basic services are specified in ISO/IEC 11574.

ANF-TC is an additional network feature which limits the number of network exchanges that a call request may transit during call establishment, e.g. to protect the network against indefinite looping. There is no user involved in the provision or operation of ANF-TC.

Additional network feature specifications are produced in three stages, according to the method described in CCITT Rec. I.130. This International Standard contains the stage 1 and stage 2 specifications of ANF-TC. The stage 1 specification (clause 6) specifies the general feature principles and capabilities. The stage 2 specification (clause 7) identifies the functional entities involved in the feature and the information flows between them.