本国际标准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参考点处支持中转柜台附加网络功能（ANF-TC）的信令协议。ANF-TC是一种限制呼叫设置请求可能通过的转接PINx数量的功能，例如，保护网络免受无限循环。Q参考点在ISO/IEC 11579-1中定义。服务规范按照CCITT建议I.130中规定的方法分三个阶段制定。本国际标准包含Q参考点的第3阶段规范，并满足ISO/IEC 15055中第1阶段和第2阶段规范确定的要求。 ANF-TC的信令协议与基本电路交换呼叫控制（如ISO/IEC 11572所规定）和呼叫独立（面向连接）信令连接（如ISOIIEC 11582所规定）的信令协议相关联。本国际标准还规定了额外的信令协议要求，以支持ANF-TC和其他补充业务与ANF之间Q参考点的交互。本国际标准适用于可互连形成PISN的PINX。

This International Standard specifies the signaling protocol for the support of the Transit Counter additional network feature (ANF-TC) at the Q reference point between Private Integrated Services Network Exchanges (PINXs) connected together within a Private Integrated Services Network (PISN). ANF-TC is a feature that limits the number of Transit PINXs that a call setup request may be routed through e.g., to protect the network against indefinite looping. 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 CCITT Recommendation I. 130. This International Standard 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 15055. The signaling protocol for ANF-TC operates in association with the signaling protocols for basic circuit switched call control (as specified in ISO/IEC 11572) and call independent (connection oriented) signaling connections (as specified in ISOIIEC 11582). This International Standard also specifies additional signaling protocol requirements for the support of interactions at the Q reference point between ANF-TC and other supplementary services and ANFs. This International Standard is applicable to PINXs that can interconnect to form a PISN.