Purpose and Scope of this ISSI Overview The purpose of the ISSI Overview is to provide an informative overview of key technical aspects and considerations supporting specification of the ISSI. This document serves as the umbrella document for the ISSI document suite. It includes a high-level overview of the ISSI features and services consistent with the TIA-102 Documentation Suite Overview [102]. This document also identifies ISSI-related documents that have been published and documents currently in progress as well as future ISSI considerations. In addition@ this document provides an overview of trunked and conventional capabilities and architectures supported by the ISSI@ and cites selected references relevant to obtaining further information on the topics presented in this Telecommunication Standards Bulletin (TSB). The architecture discussion also presents the Fixed Station Subsystem Interface (FSSI) and the Console Subsystem Interface (CSSI) and how these interfaces relate to the ISSI in order to provide a more complete picture of the extended communication capabilities discussed in this document. The scope of this document is restricted to the description of an ISSI that supports wide area voice services@ packet data services@ and supplementary services via interconnection of RFSSs (from the same or different manufacturers) using Internet Protocol (IP)-based networks as described in the TIA-102 Documentation Suite Overview [102].