Centrally-controlled telephone PBX - stores line-group address of wanted line in queue store for comparison with released lines

摘要

The telephone private branch exchange allocates lines using existing storage devices and depending on the conditions of lines in groups of lines. The addresses of groups of lines in which a free line is wanted is stored in a queue store. When a line becomes free this fact is signalled to the operator and line reservation initiated which leads to the operator connecting his set to the free line. Checks are periodically performed to find lines that have become free. When a free line is found within any group the contents of the store are compared with the waiting requirements in the queue store.