In article ,
JANA wrote:
Phones need 48 Volts DC with an in series of 600 to 800 ohm source. The
ring is 96 Volts at 25 Hz.

That's the spec to allow for vast voltage drop over the miles of cable
between phones. Just to get two to talk to one another 9 volts will work
just ok. Indeed if you're talking about old non electronics phones with
carbon mics 1.5 volts will be ok for short runs.

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*Proofread carefully to see if you any words out or mispeld something *

Dave Plowman London SW
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