ISO 17575-2:20 16定义了如何通过适用于此应用的任何通信堆栈和介质来传送ISO 17575其他部分中定义的全部或部分数据元素结构。它仅适用于移动通信链路（尽管有线链路，即后台连接，可以使用相同的方法）。 为了建立到初始化通信信道的服务呼叫序列的链路，需要寻址消息的接收和转发有效载荷。ISO 17575这一部分提供的定义包括所需的独立于通信介质的服务，由抽象应用程序编程接口（API）表示。 通信接口被实现为前端(FE)系统选择的编程环境中的API。后端（BE）API的规范超出了ISO 17575这一部分的范围。 本API的具体定义超出了ISO 17575本部分的范围。ISO 17575的这一部分规定了一个抽象API，它定义了具体API的语义，如图3及其协议实施一致性声明（PICS）形式（见附录B）所示。具体API的示例见附录C。在抽象和具体通信API之间没有区别的情况下，可以使用术语“通信API”或仅仅是“API”。 ISO 17575-2:20 16还提供了相关API语句结构的详细规范，以及如何实现它及其在复杂收费集群（如EETS）中的作用的示例（参见附录A至附录E）。 介质选择策略、证书处理和加密机制超出了ISO 17575这一部分的范围。

ISO 17575-2:2016 defines how to convey all or parts of the data element structure defined in other parts of ISO 17575 over any communication stack and media suitable for this application. It is applicable only to mobile communication links (although wired links, i.e. back office connections, can use the same methodology). To establish a link to a sequence of service calls initializing the communication channel, addressing the reception of the message and forwarding the payload are required. The definition provided in this part of ISO 17575 includes the required communication medium independent services, represented by an abstract application programming interface (API). The communication interface is implemented as an API in the programming environment of choice for the Front End (FE) system. The specification of the Back End (BE) API is outside the scope of this part of ISO 17575. The definition of this API in concrete terms is outside of the scope of this part of ISO 17575. This part of ISO 17575 specifies an abstract API that defines the semantics of the concrete API as illustrated in Figure 3 and its protocol implementation conformance statement (PICS) proforma (see Annex B). An example of a concrete API is presented in Annex C. Where no distinction is made between the abstract and concrete communications APIs, the term "communications API" or just "API" can be used.

ISO 17575-2:2016 also provides a detailed specification for the structure of associated API statements, an example on how to implement it and its role in a complex toll cluster such as the EETS (see Annex A to Annex E). Media selection policies, certificate handling and encryption mechanisms are outside of the scope of this part of ISO 17575.