ty, are distributed to the TCEs, ACEs and DSEs via a Clock and 3. X.25 DCE functions for connection to the Network Service Tones distribution (CLTD) subsystem. Centre. 4. Frame handler functions for D-channel multiplexing. 5. Packet Handler interface. 32.6.1.8 Service Circuits Module (SCM) The SCM, provides tone handling facilities for subscribers with 32.6.1.12 Trunk Test Module (TTM) push-button telephone sets and also for exchanges that use multi- frequency (MF) senders and receivers for inter-exchanges signall- The TTM provides facilities for automatic, semi-automatic and ing. Optionally, a conference call facility can be included. manual testing of trunk devices. NETWORK JOB-HANDLER SYSTEM TOOLS LOGICAL EXCHANGE CONFIGURATION - BERGAMO - OWCOI - SCANWOROSCIATE SACEPLCTD SACETRA SACEADM SACEPBX LCEID ASMECSX DTMTCF SACECHRG SPARE CCSMN7 not ack alarms 29/11 13:32 (O&M) Figure 32.5 An operations and maintenance (O&M) screen display 32/12 Telephone exchanges 32.6.2 System 12 general software Measurement and Data collect procedures using simple Man configuration Machine Command (MMC). Efficient diagnostics and repair procedures, normally involving The system 12 on-line software contains the following main areas: the replacement of a printed board assembly (PBA), which gives a low mean time to repair. Minimum physical contact with the equipment, made possible 1. Operating system and network handler, managing all exchange by the use of the MMC facility. This facility is used to provide resources and control the SW in each CE. most of the O&M related functions, e.g. subscriber administra- 2. Input/output software, interfaces between the application (user) tion, corrective maintenance. software and the peripheral devices. 7. Easy modification of exchange data (routeing tables etc.) by the 3. Man Machine (MMC) software provides a part of the interface use of MMC commands. Modified tables etc. are automatically between the MMC devices and the applications software. stored in back up mass memory (e.g. disc) to ensure t