Design Characteristics of Digital Telephone Switching System
The Central Office (CO) digital switching system shall:
5.4.1 Be part of a family of exchange switches of different capacities.
5.4.2 Include exchanges, and remote switching units.
5.4.3 Have the capability of combining local, tandem and transit (toll) exchanges.
5.4.4 The exchanges shall be stored program control, digital electronic switching systems, capable of applications as local and remote exchanges. The exchanges shall be suitable to operate as hosts for Remote Line Switches (RLS).
5.4.5 The exchanges specified here, shall form the basis of the present and future Integrated Services Digital Network (ISDN) of Saudi Aramco. Services introduced in the future shall be compatible with all applicable ITU-T Recommendations, providing switched connections for streams of 64 kb/s.
5.4.6 Incorporation of ISDN services shall not cause service interruptions or changes in the existing grade of service.
The actual requirements of the above two ISDN subparagraphs 5.4.5 and 5.4.6, shall be verified during the conceptual and detailed design for each individual project, prior to the final design and implementation of the project.
5.5 Traffic Handling and Switching Facilities
The switching equipment shall handle the following types of traffic:
5.5.1 Originating Traffic
The traffic from subscribers in an exchange, destined either for the same exchange or for other exchanges, the latter case is considered outgoing traffic.
5.5.2 Terminating Traffic
The traffic in an exchange destined for its own subscribers, originating either in that exchange or from other exchanges, the latter case is considered incoming traffic.
5.5.3 Transit Traffic
The traffic in transit through an exchange, originated in another exchange and destined for a third exchange.
5.5.4 Operation and Maintenance Traffic
Is an administrative traffic generated by and destined for network maintenance and operation and not for ordinary subscriber service.