| 摘要 |
Signalling and call set-up process in communications systems with ring topology. For use in communications systems with a ring topology 1 which use a common channel for signalling and which use a protocol by means of which, at any moment, there is one unit of the ring which is operating as master unit. The objective is to minimise the interchange of information between the units connected to the ring during the call set-up process. Each unit, during its time interval, sends out a complete signalling message which the other units receive, by which they know the status of the rest of the units and of the communications channels of the system. When a user asks for communication to be established with another unit, the originating unit determines whether it is possible to establish the communication, such that, if so, it sends a single message to the destination unit which answers with another single message, when the master unit assigns it the signalling channel. <IMAGE>
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