Remote Switching Maintenance and Subscriber Unit Network Peripheral Interface Module Module Control Control Common Channel Clock & Tone Module Module Control Control Service ISDN Packet Circuits Trunk Module Module Control Control Figure 32.3 System 12 modules 32/10 Telephone exchanges Synchronous Transmission Asynchronous Interface Transmission Interface Terminal Control Element Terminal Digital Switching Network Terminal Interface Terminal Circuits Tones and Speed Time of day Control Distribution Microprocessor Memory Figure 32.4 General structure of a Terminal Module 32.6.1.5 ISDN Remote Interface Module (IRIM) 32.6.1.9 Common Channel Module (CCM) The IRIM, which is equipped as a paired module, is similar to the The Common Channel Module (CCM), performs signal processing DTM but is used to control Remote Subscriber Units (RSUs) and to for CCITT Number 7 Common Channel Signalling (CCS) systems. interface them (singly or in multi-drop) to a host System 12 ex- The module can be used either for purely common channel signall- change. The lines can be analogue or ISDN lines. ing or for ISDN environments. 32.6.1.6 Support and Peripherals Modules (SPM) 32.6.1.10 ISDN Subscriber Module (ISM) An SPM, comprises a Support Module (SUM) and a Computer Peripherals Module (CPM), each of which has a TCE and a termi- The ISDN Subscriber Module (ISM), Provides up to 64 basic access nal. Each SPM is duplicated for reliability. There are two types of (BA) connections for ISDN subscribers or ISDN PABXs and con- trol the handling of related ISDN calls. 1. Maintenance SPM. 2. Administration SPM. 32.6.1.11 ISDN Packet Trunk Module (IPTM) The IPTM can perform several functions always combined with the 32.6.1.7 Clock and Tones Module (CTM) trunk module function. Those functions are: The CTM, generates a clock timing signal, a range of PCM encoded audio tones and the TOD signal for distribution throughout the 1. MTP functions for CCITT N7 signalling. exchange. The outputs of the CTM, which are duplicated for relia- 2. PRA interface. bili