摘要 |
An electronic switch (29) for automatically connecting a subscriber telephone instrument (31a, 31b, 31c, or 31d) to either of two telephone signal paths (27 or 28) is disclosed. Outbound calls are selectively routed to one or the other of the two telephone signal paths, based on the nature of the initial digits generated by the subscriber. Local calls are sent to a local exchange carrier (23a) and toll calls are sent to an inter-exchange carrier (25) via a transmission medium that may also carry other signals, such as cable television or utility energy management signals. In the event the normal path is out of service, outbound signals are sent via the other path. Inbound signals from either path are automatically routed to the subscriber. Signal routing is completely transparent to the subscriber.
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