| 摘要 |
A telephone exchange transmits audible signals to a subscriber line to indicate exchange or network conditions. The audible signals to be transmitt ed to the subscriber line are selected (means 15) from one or more available audible signal sources (14, 16, 17, 18, 19) according to the contents of a store location (20) for that subscriber line. Further store locations (25) a re provided for each subscriber line to enable selection (means 21) of further audible signal sources (22, 23, 24) dependent upon the condition. The subscriber may alter the contents of his or her store location (20, 25) by dialling a special code.
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