ISO/IEC 15054:2003规定了在专用综合业务网络（PISN）内连接在一起的专用综合业务网络交换机（PINX）之间的Q参考点处支持附加网络功能呼叫拦截（ANF-CINT）的信令协议。 ANF-CINT是一种额外的网络功能，它可以将由于某些条件而无法完成的呼叫重定向到预定的被拦截用户。 ISO/IEC 11579-1中定义了Q参考点。 按照ETS 300 387规定的方法，分三个阶段制定服务规范。ISO/IEC 15054:2003包含Q参考点的第3阶段规范，并满足ISO/IEC 15053中第1阶段和第2阶段规范确定的要求。 ANF-CINT的信令协议在ISO/IEC 11572中规定的基本电路交换呼叫控制信令协议的基础上运行，并使用ISO/IEC 11582中规定的补充业务控制通用程序的某些方面。 ISO/IEC 15054:2003还规定了额外的信令协议要求，以支持ANF-CINT与其他补充业务和ANF之间Q参考点处的交互。 注:对Q参考点的信令协议没有影响的其他交互可在相关的1级规范中找到。 ISO/IEC 15054:2003适用于可互连形成PISN的PINX。

ISO/IEC 15054:2003 specifies the signalling protocol for the support of the additional network feature Call Interception (ANF-CINT) at the Q reference point between Private Integrated services Network eXchanges (PINX) connected together within a Private Integrated Services Network (PISN). ANF-CINT is an additional network feature which enables calls that cannot be completed due to certain conditions to be redirected to a predetermined intercepted-to user. The Q reference point is defined in ISO/IEC 11579-1. Service specifications are produced in three stages and according to the method specified in ETS 300 387. ISO/IEC 15054:2003 contains the stage 3 specification for the Q reference point and satisfies the requirements identified by the stage 1 and stage 2 specifications in ISO/IEC 15053. The signalling protocol for ANF-CINT operates on top of the signalling protocol for basic circuit switched call control, as specified in ISO/IEC 11572, and uses certain aspects of the generic procedures for the control of supplementary services specified in ISO/IEC 11582. ISO/IEC 15054:2003 also specifies additional signalling protocol requirements for the support of interactions at the Q reference point between ANF-CINT and other supplementary services and ANFs. NOTE Additional interactions that have no impact on the signalling protocol at the Q reference point can be found in the relevant stage 1 specifications. ISO/IEC 15054:2003 is applicable to PINXs which can interconnect to form a PISN.