| 摘要 |
To allow an observer at any remote subset on a telephone network to observe the quality of service provided to customers in a local area thereof, a service observing unit is connected to each line and trunk to be observed at the local area and to an incoming trunk from an adjacent central office. When the remote observer dials a connector number at the central office assigned to the service observing unit, an observer line connector connects the unit to the remote observer and transmits an identity tone thereto. The remote observer must then dial a security access code comprising a plurality of multi-frequency signals with established inter-signal spacing in a given sequence within a predetermined time period, or a timing and disconnect circuit within the unit releases the connection established by the observer line connector. If a correct code has been dialed, an inhibit signal is provided to the timing and disconnect circuit and an idle tone is transmitted to the remote observer. A plurality of selectors and connectors, one for each trunk or line to be observed, are then enabled by a reset signal. The first of these observed trunks or lines to have a calling signal thereon is detected by its corresponding selector which then supplies an inhibit signal to the remaining selectors and connects its line or trunk through its connector to an amplifier, and a hybrid bridging network to the remote observer. To select another line or trunk, the observer dials the last multi-frequency signal of the security access code so that a reset signal is supplied to all the selectors. To disconnect, the remote observer may place his subset on-hook or dial a disconnect multi-frequency signal. A solid-state embodiment of the unit is also discussed, as is a modification allowing selective access by the remote observer to a plurality of trunk or line groups.
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