ETSI EN 300 392-3-1定义了地面通信系统间接口（ISI）互通的一般方面 集群无线电（TETRA）系统支持语音加数据（V+D）。这些规定的一般概念是 TETRA系统之间ISI操作的基础。它介绍了应用程序中使用的附加网络功能（ANF） ISI，并规定:通用协议机制，称为ISI通用功能协议（ISI GFP），定义 每个ANF的基础是什么；以及ISI的安全要求。ISI GFP规范适用于任何支持 ISI。ISI的安全要求仅适用于支持ISI认证或加密的SwMIs。 除ISI总体设计外，本文件还包括系统间接口的互通 以下其他子部分:附加网络功能-ISI个人呼叫（ANF-ISIC）；附加网络功能——ISI群组呼叫（ANF-ISIGC）；附加网络功能——ISI短数据服务（ANF-ISISDS）；和附加网络功能——ISI移动性管理（ANF-ISIMM）。

ETSI EN 300 392-3-1 defines the general aspects of interworking at the Inter-System Interface (ISI) for Terrestrial Trunked Radio (TETRA) system supporting Voice plus Data (V+D). Those specify the general concepts which are the basis of the ISI operation between TETRA systems. It introduces the Additional Network Features (ANFs) used at the ISI, and specifies:the general protocol mechanism, called ISI Generic Functional Protocol (ISI GFP), upon which the definition of each ANF is based; andthe security requirements for the ISI.The ISI GFP specification applies to any TETRA Switching and Management Infrastructure (SwMI) which supports the ISI. The security requirements for the ISI only apply to SwMIs which support authentication or encryption over the ISI.Besides the ISI general design, the present document, interworking at the Inter-System Interface comprises the following other sub-parts:Additional Network Feature - ISI Individual Call (ANF-ISIIC);Additional Network Feature - ISI Group Call (ANF-ISIGC);Additional Network Feature - ISI Short Data service (ANF-ISISDS); andAdditional Network Feature - ISI Mobility Management (ANF-ISIMM).