| 摘要 |
A normally straight-through connection from a computer fax modem to a fax machine, or other fax sender to fax receiver, is briefly interrupted under battery power to supply the fax modem with a simulated dialtone and the fax machine with a simulated ring signal, which is supplied via a DC-to-DC converter activated by the same clock signal from which the dialtone and simulated ring signal are derived.
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