Remote Line Switch (RLS) of Digital Telephone Exchange System
a) The RLS equipment shall be digital with Stored Program Control (SPC), connected to a local exchange called a host exchange, and shall be able to perform the following functions:
1. Perform intra-RLS switching of line-to-line calls within the remote switch itself.
2. Gain access to the inter-office network by switching through the host exchange.
3. Provide local service and billing at the remote location when the link to the host exchange is inoperative, with zero (0) call loss.
4. Operate as an unattended switching unit.
5. Be connected to the host exchange with PCM links.
6. Provide direct trunking to switching entities other than the host exchange.
b) The host exchange equipment shall perform the following functions for the remote line switch on a centralized basis:
1. Store data for individual calls.
2. Perform billing functions.
3. Maintain office records.
4. Offer maintenance and test capabilities.
5. Partially control calls of the RLS.
5.21.2 Administration and Maintenance
All the administration and maintenance work of the RLS, including traffic measurements and monitoring, line testing, malicious call tracing, billing and system diagnostics, modification of classes, etc., shall be accomplished by the host exchange through data links.
The service quality and the number and type of services of the RLS’s subscribers shall be the same as those connected to the host exchange.
The host exchanges shall be equipped with means for remote testing and remote alarm signaling of the RLS.
5.21.3 Intra-RLS Call Function
RLS shall be able to process the total intra-RLS calls including ISDN calling and packet switching with no host support, even when all links between the host exchange and the RLS fail. In case of such failure, no calls shall be lost by the RLS.
5.21.4 Range of Applications
In general, the range of application for the RLS shall be at least 200 digital trunks or 2,000 lines. The exact number of trunks/lines will depend upon each individual project’s requirements. Trade offs can be made between lines and trunks at approximately a 10:1 ratio. The RLS shall provide service without service interruption and without changes in the number, type and quality of service offered to subscribers.
5.21.5 Billing Data
The call charging data of the RLS shall be sent to the Saudi Aramco billing system of the host exchange. If the link from the RLS to the host becomes inoperable, RLS billing data shall be retained and transferred to the host upon restoration of the link between the RLS and the host.